"High quality" depends on how you measure quality. If you're judging by looks and how many buttons it has, then yes, I think it takes the cake. But I honestly appreciate the current Linux design paradigm. GTK and QT are both awesome GUI toolkits, and compliment each other nicely. GTK does a wonderful job of filling the MacOS gap, by making it easy to create simple but effective UIs. QT, on the other hand, offers a more stable and "complete" experience, pretty much catered towards people familiar with the Windows/.NET development workflow.

Like the other commenter said, I just don't see anywhere Linux is particularly lacking. It has first class support with DAWs like Reaper and Bitwig, it has pretty great video editing chops with apps like Davinci Resolve and Kdenlive, and it almost has a complete photography setup, at least once GIMP switches to GTK+ and Darkroom gets a few more features. All of those are "high quality" apps, and they're also free: a pretty massive distinction from the MacOS software you might pit against it.

I sort of simultaneously see that that's true, but also don't personally feel I'm missing anything except Fusion360.

But maybe that's just the extra motivation I need to use something else like FreeCAD or OpenSCAD with more git-able files anyway.

(I also use Arch btw.)

Sure, you might only miss one or two apps. And I might only miss one or two apps. But it's probably different apps for both of us, and I think that probably generally holds true for the vast majority of people.

The Linux Desktop is 95% of the way there, no question about it. But that 5% is different for each individual, and ultimately, it matters.

I mean, we can't kid ourselves here: none of these operating systems are 100% of the way there. By your logic, MacOS isn't 100% of the way there because it can't play the same games as Windows, and Windows isn't 100% of the way there without running Final Cut and Logic. The issue with that metric is that it will grossly play against your favor if we're being diminutive about the amount of software that's on each respective platforms.

It really depends what you do on your computer. I think a better way to look at it is that each of these OSes will do 90% of the things you want them to, and you just need to pick and choose which 10% matters the least to you.