The inconvenient truth here is also that following the system theme is an anti-feature for most apps. On the desktop, you want your app window to be recognizable at a glance, meaning the primary color should be the brand color, etc.
I currently have open Chrome, Spotify, Discord, Aseprite, and Zed. All of them look completely different, and that's actively helpful for me, the user.
It's nice to follow the system's light/dark setting, and obviously the behavior of basic UI controls should be unsurprising, but beyond that there's no point in "consistency".
This. So often features to use system colors can cause apps to be unreadable or just look like crap. The first time I get a bug report that people can't read something I will lock the colors the down, I just don't have time for that.
Who says the system theme is well designed at all? Back in the 1980s you could count on most text color combinations on a Commodore 64 or an IBM 3279 or a PC with a CGA working.
Today it is absolutely normal to type
on a Linux machine out of the box and if you are running X or Wayland some of the file names are dark blue on a black background and completely un-readable. To be fair, if you are logging into a Linux machine on Windows with ssh on CMD.EXE or most terminal software you get similarly poorly chosen colors. (To be fair, MacOS does do better!)As a web developer it pisses me off because I am expected to follow
https://www.w3.org/WAI/standards-guidelines/wcag/
and regularly my management gets legalistic looking documents from customers complaining that we only have 6.5:1 contrast on something and you know what I do... I fix it. I wouldn't send anything to my tester that was unreadable and if I did I'd expect her to put in a ticket and I would... fix it. When MUI computes the coordinates wrong and something draws 20px right of where it should be... I fix it.
Whenever I've put similar tickets to the various parts of the Linux desktop mafia they close it as "won't fix" and often give me a helping of verbal abuse. Even Microsoft occasionally fixes something (even if half a decade late) and their people are polite.