the good thing is that virtually everyone uses GNOME and KDE, so the small issues are mostly encountered by more advanced users with custom setups. The main point is that app developers can now develop apps that will work anywhere that implements the required features, and if it doesnt, then too bad, show an error message. Its the same kind of problem with, for example, webcams. The user may or may not have a webcam connected, in which case you display an error popup with a clear message that it does not work because the feature is not implemented. They could go into fallbacks but those are usually platform/desktop specific (which goes against the point of building using the standard stack)

Eh, it's mostly everyone agrees but Gnome doesn't

There was always a need for a specific system dependency like for the file picker. There was no universal API that uses a system provided way to have a file picker. It had to be hacked together by adding dependencies to the app and everything that comes with this

The Linux part was never a problem. The userspace is.

For the proper opensource apps, this can be fixed by the package maintainers (shout-out to the real heroes!).

For proprietary, compile-once run anywhere apps, that was always a problem. For more info, I recommend this great FOSDEM talk by Simon McVittie from Collabora.

I'll give it a try. Thank you!