I'm typing this right now on my 2015 13" MacBook Pro (retina display, of course). Even with the retina display, I may find myself squinting at text displayed at certain sizes (say, 10pt).
I know what you are talking about. However, you don't seem to understand what I'm talking about.
There seems to be a
lot of misunderstanding about the whole Retina/HiDPI/Scaled thing and Apple using "looks like 1920x1080" to describe something that doesn't look like 1920x1080. A simplified, but IMHO non-misleading version (with some of the ifs and buts relocated to footnotes) is:
In MacOS you
can't[1] actually change the resolution of a 4k/5k/Retina display the way you could with standard def.
The display always runs at native resolution[2].
The "looks like" resolution quoted in the displays control panel
isn't the resolution[3]. "Looks like 1920x1080" just means that the fixed-size UI elements (menus, icons, dialogs etc.) are the same
physical size as they would be on a 1080p screen. The actual "resolution" of the display is much better than the "looks-like" value [4]
and any application that lets you set the font size/zoom can take advantage of that.
The
optimum mode for any display is always "looks like" half the actual screen resolution - i.e. "looks like 2560x1440" for a 5120x2880 (5k) display. Jumping through a hoop and selecting 1:1 mode just makes the UI too small. Other modes give a slightly softer 'edge' to things and also place more demands on the GPU and VRAM, but they're very usable.
"HIDPI" mode means that the UI elements are rendered with twice as many pixels to make them a more usable size on a "retina" screen. Mostly, any mode
without this is near-unusable with mortal eyesight on a 4k display smaller than about 30" and with Apple Retina displays all of the non-hoop-jumpy-through[5] modes are HiDPI[6][7].
Bottom line: on a retina display you can choose a "scaled" screen mode that makes UI elements the same physical size as they would be on a lower resolution display, but at a level of detail approaching 'native'. You get several choices of text size. You just can't do that on a standard-def display.
get a 2018 Mac Mini i3 with 8gb of RAM and a 128gb SSD.
I wouldn't pair that model with a 4k display because the scaled modes
do need a half-decent GPU and adequate VRAM. The Mini has a fairly mediocre GPU that has to 'steal' its VRAM from the system RAM. From other comments here, just upping the RAM to 16GB might be enough, though.
The sharpness vs. size thing is complicated as well - I've got an ancient pre-retina version of Photoshop Elements that
does look fuzzy in retina mode and while it ought to be perfectly readable, if my eyes are tired it drives them crazy trying to focus on it.
[1]... without ticking a box to 'show low resolution' modes or installing a third-party utility
[2]... i.e. the image sent from the computer to the display is always at the native resolution of the display. With standard def, the computer would happily send, say, a 1024x768 signal to a 1920x1080 and let the display sort it out (usually badly).
[3]... and the values you see in "system report" may or may not be, depending on how the display is connected.
[4]... e.g. "looks like "2560x1440" on a 4k display is actually 5120x2880 downsampled to 3840x2160 and contains substantially more detail than you would get on an actual 2560x1440 screen, even if its not quite 'full 4k'. On a 5k display, that's just 5120x2880 with twice as many pixels in the system fonts, menus, icons etc.
[5] At some time in my life I must have watched way to much
Buffy...
[6] Windows has a user-settable DPI which lets you tailor the UI size exactly to the screen and your preferences, and would be technically much better if only all applications supported it properly. MacOS just has two settings - low and hi - and uses the render-huge-and-downsample mode instead.
[7] Its 2019 and the vast majority of Apps either have HiDPI versions of their icons with more detail or render stuff using resolution-independent vector graphics (which also happens with fonts). Some ancient apps not updated since 2012 don't so the system just doubles-up the pixels.