> UI framework balkanization has always been, and remains a hideous mess.

Amen.

But, which OS doesn't have this problem? I'm currently running windows on a work laptop and even freaking first-party apps have a different look and behave differently from one another. Teams can't even be assed to use standard windows notifications! And don't get me started on electron apps, of which most apps are nowadays, each coming with their own look and feel.

Also, have you tried switching from light to dark mode, say at night? The task manager changes only partially. The explorer copy info window doesn't even have a dark mode! On outlook the window controls don't change colour, so you end up with black on black or white on white. You can't possibly hold up windows as a model of uniform UI.

So while I agree that this situation is terrible, I wouldn't pin it on the linux ecosystem(s).

> Every other major OS can deal with [high dpi].

Don't know about mac os, but on Windows it's a shitshow. We use some very high DPI displays at work which I have to run at 200%, every other screen I use is 100%. Even the freaking start menu is blurry! It only works well if I boot the machine with the high-dpi display attached. If I plug it in after a while (think going to work with the laptop asleep), the thing's blurry! Some taskbar icons don't adapt, so I sometimes have tiny icons, or huge cropped ones if I unplug the external monitor. Plasma doesn't do this.

IME KDE/Plasma 6 works perfectly with mixed DPI (but I admit I haven't tried "fractional" scales). The only app which doesn't play ball 100% is IntelliJ (scaling works, it's sharp, but the mouse cursor is the wrong size).

> Audio filtering is a pain to set up.

What do you mean? I've been using easyeffects for more than five years now to apply either a parametric EQ to my speakers or a convolver to my headphones. Works perfectly for all the apps, or I can choose which apps it should alter. The PEQ adds a bit of a latency, but applications seem to be aware of it, so if I play videos (even youtube on firefox with gpu decoding!) it stays in sync. It detects the output and loads presets accordingly. I also don't have to reboot when I connect some new audio device, like BT headphones (well, technically, on Windows I don't anymore, either, since for some reason it can't connect to either of my headphones at all). I would love to have something similar on windows, but the best I found isn't as polished. It also doesn't support dark mode, so it burns my eyes at night.

macOS and Windows have a much smaller set of variants, and tend to ship a single UI with everything included with OS. Even the best single desktop Linux distros will ship divergent KDE and Gnome apps.

If you want essentially perfect high-DPI support out of the box and can afford higher end displays, use macOS. It just works. I see the comments above about scaling, and to that, I say: most people will never notice. However, a Win32 app being the wrong scale? They'll notice that.

But the real display weak point of Linux right now vs Windows is HDR for gaming. That's a real shitshow and it tends to just work on Windows.