Adobe -> Affinity
Microsoft -> OpenOffice, LibreOffice, iWork apps, etc.
You are right about this though:
But that would also impact Windows. I would jump to Linux in a heartbeat if I had native support for all my needs. That is not possible, and I despise Windows so macOS is my only answer.
YOU would. Most people wouldn't.
First, why would major players like Adobe support Linux ? Out of the goodness of their hearts ? There's no real money in this.
Second, from the POV of an average customer, why Linux ? So that they could avoid spending $50 or so MS license price that is the part of their $800 laptop purchase ? The amount of headache far outweighs that.
Using Linux is fun, but it's also a huge can of stinky worms. It's not just Office.
What about email clients ? Thunderbird or Evolution look outdated, and are neither very stable nor look attractive out of the box. Some tinkering is required to make them work really well.
How about global search (an alternative to Windows Indexing or Spotlight ?) I personally liked Recoll, but it looks like a mad scientist's nightmare, and takes a while to learn and set up. So do other alternatives.
How about syncing with Onedrive or Google Drive or iCloud ? Yes there are 3rd party solutions for that, but they are either CLI that requires lots and lots of tinkering, or paid apps like Insync.
And so on... making a Linux setup to even approach the level of user friendliness of Windows is a lot of upfront work, and worse, it's a lot of user maintenance. You can set it up once - but it will get borked the next time some random developer decides to change things. Linux and customer-centric don't belong in the same sentence. It's too dependent on 3rd party tools written by volunteers.
As to Mac - people pay "Mac premium" because (a) it's trendy or (b) they expect a certain degree of polish, seamless integration between different devices, and ease of daily use. Again... this is not achievable on Linux, not without major investment.
I don't knock Linux - I love a lot about it. But it's not for an average customer who just wants a workable laptop, not without some major upfront investment and lots and lots of work. And there's simply no business case in this, at least at the present time.
If anything, the biggest threat to MS (but not to Mac) is Chromebooks. A high end Chromebook combined with a good Android phone comes surprisingly close to the user experience you'd get with Mac and an iPhone. It works, it rarely if ever has issues, it's fast and deeply integrated.