I disagree. It's not very good for anything.
You're not listening very carefully, it seems. I get that it doesn't fit for
your situation. That doesn't mean that it's ill-suited for
everyone else's situation. My whole point was that it's useful
in some situations. You started off by disagreeing with that full-stop. Sounds like you want to stamp out Markdown for everyone because it doesn't work well
for you.
It's very difficult to parse, it is not entirely standardised, seems to have weird extensions all over the place, has terrible embedding and image support and just doesn't work for a lot of things at all (letters, email comms for example). It also has no structure outside the document itself other than naive hyperlinking which doesn't work anywhere other than the destination you upload it to.
The fact that there are parsers for Markdown available for nearly every programming language on the planet would seem to contradict your first statement. And
English is also not entirely standardized and has weird extensions all over the place (slang, dialects, specializations), yet we continue to use it quite beneficially to communicate, millions of times a day - would you argue in favor of getting rid of English, because it's not standardized?
(As far as standardization goes, lots of Markdown implementations these days support the CommonMark standard.)
I have used Markdown numerous times for email messages where I wanted particular formatting, because WYSIWYG editors tend to be sloppy and hard to control - I'll write the Markdown-formatted text in a suitable tool (e.g. Drafts or MacVim, depending on how involved it is), and then copy it out as Rich Text and paste it into Mail, without having to mess around with the target app's WYSIWYG formatting controls.
As far as structure goes, one of my most common uses for Markdown is writing all manner of notes for myself in
Obsidian, which has a very rich system for Wiki-style linking between notes and to specific points in notes. It also supports MathJax and LaTeX for formula writing, for what it's worth, though I don't make use of that, and has a built-in canvas system for drawings, along with a well-regarded extension (Excalidraw) for more elaborate drawing.
As for people writing scientific papers in markdown, this does actually happen to some naive people who think they know better.
I'm glad to see that we both agree that people should not be trying to write scientific papers in Markdown. Again, it's a tool that has a niche, and scientific papers and such are generally well outside of that niche. Last I checked, LaTeX was still the standard there. You can run Markdown through Pandoc to get at least a start on the equivalent LaTeX document, if someone is foolish enough to try to write such a thing in Markdown.
Note taking. Actually a lot of this goes on iPads now or even paper. One of our lead engineers has a physical notebook and a pen. This is after years of trying to use OneNote, Goodnotes etc. On the academic side, thread bound physical notebooks are still very much a thing in mathematics and engineering because when it comes to representing arbitrary information and diagrams, things like markdown become instantly useless. No one is going to sit there and type out MathML, LaTeX etc when you can just write it. iPads with Goodnotes (or Noteful in my case) are used regularly but that hasn't phased out paper.
Note taking on paper is downright
dangerous - because there is no backup, no easy duplication, no portability, and no search-ability. Lose your notebook and hundreds/thousands of hours worth of notetaking could be gone forever. If you want to make a copy of something for someone, you're what, reduced to standing in front of a copy machine for a while? Or photographing the pages? Or awkwardly scanning the pages of a notebook 1-2 at a time on a flatbed scanner? (And what if there's something else on the page you don't care to share?) And if you leave the notebook in one place, you have zero access to it in another place - if I think of something to look up, or modify, when I'm away from my Mac, I just take out my iPhone, open the Obsidian app and I have complete access to all the same Markdown-formatted notes that are on my Mac, fully synced between the two (and my iPad as well). Similarly, if I want to send someone a note, it's a simple matter of copying and pasting, not scanning pages out of a paper notebook. And I can find anything in thousands of notes in a couple seconds, with a simple search query - paper can't do that, especially if you have a large stack of paper notebooks (and considering that you may be searching
because the item you seek was written down in an unexpected place).
You're attacking Markdown for not being able to do arbitrary diagrams and such - it's like attacking a car for being a very ineffective submarine - sure, but that doesn't mean cars have no use. Despite this, there are people who employ Obsidian quite effectively for note taking involving diagrams and formulas and such, as it has a wide variety of extensions for these (it's not something I do, but there are people using it quite enthusiastically this way, who are very happy with the results). Something like GoodNotes or Notability, on an iPad, is often much more suitable for quickly taking down information that involves diagrams and formulas and such, and it's way better than paper for all the reasons noted above, primarily backup.
Reply writing. We mostly use email for this, and there is no markdown support in email. In fact a lot of the time we email each other PDFs with scanned hand written notes or pdfs from goodnotes or link to O365 for draft technical documentation (which sucks but at least everyone can use it).
As mentioned, I happily use Markdown for composing email responses,
when the occasion warrants it, and translate to rich text to paste into email. You make it sound like there is an unpassable wall here - quite the opposite,
if it suits you. I have frequently done this in cases where the email I'm composing draws from text that I already have in Markdown format. (I should point out that reply writing also meant on Reddit, where everything is fundamentally Markdown.)
Other small tasks. I use Apple Notes for semi structured information. Things like recipes, trip planning or writing the faculty WiFi password down. That has nice things like checkable, sortable lists which again are not possible in any reasonable form in markdown.
I use Markdown (mainly in Obsidian but also for a lot of other random notes where it's simply a good convention for adding information) for all manner of small tasks.
I avoid Apple Notes like the plague, because the import/export capabilities are severely lacking, and there's no good interface for working with it from other tools (on my Mac I can easily access all my notes in Obsidian directly from the filesystem using all sorts scripts and tools, plus Obsidian offers thousands of plugins to do all sorts of things, from the mundane to the esoteric) - whatever Apple provides for Notes, that's what you get (and all you get). Also, it suffers from the usual WYSIWYG slop - is that a bold space or a regular space between those words? who knows? - after a bunch of formatting revisions over time, you have only a vague idea of what your text
looks like, not what characters and formatting are actually in the file - I much prefer the precision of Markdown (or, frankly, any other text-based markup, but Markdown is simplest) in this situation.
As far as things like checklists go, I use them in Obsidian all the time (it supports that common extension to Markdown), and if I want sorting, a keypress takes me out to MacVim where I can rearrange/transmogrify the text of a Markdown-formatted Obsidian note in any arbitrary way I want (running a section of a file through sort(1) is a common thing to do). Your "not possible in any reasonable form of Markdown" falls flat, plus you're conflating a markup language / file format with an
app (Apple Notes) - trying to compare apples and oranges. Oh, and I never write down passwords outside of a password manager.
Generally it's just not very useful ...
That's an odd thing to say to a bunch of people who are
using it very effectively.
Of course that's because it's written by software engineers (I occasionally cross into that) who mostly seem to be incapable of reasoning about anything outside of their domain.
The casual insult aimed at software developers is noted. I'm sure there are numerous retaliatory insults that could be aimed at your field, but I'm not going to bother. (And it should be noted, the original author of Markdown is a
writer.)
