One of the issues is that most of the money comes from big corporate sponsors that are nearly exclusively going to be running Linux on a server with no GUI.
These businesses have no interest in trying to develop a desktop UI when Mac OS and Windows work fine already and someone else is doing all the work for it already.
It's not just corporate sponsors though. Many Linux developers and most hardcore Linux nerds have an irrational distain for GUIs. They think that Vim is the best thing since sliced bread and if you don't want to use the terminal to set up WiFi then you're a noob that belongs on Windows.
Not everyone is like that but that's definitely the prevailing attitude. A good example is the regular hate that SystemD receives. Nobody wants a modern system that supports hotplugging and GUI configuration. They think you should edit init.rc files by hand and reboot your desktop (laptop? what's that?) whenever you plug something in.
The reason people like Vim isn't because they hate GUI's. I use a Mac because I like the GUI, but I still do most of my development in Vim because I'm more productive in it. Most of these hardcore Vim (or Emacs) users stay that way because they've built up years of muscle memory and customizations that makes it the most productive editor for them. I also use VS Code and for some stuff I work faster in VS Code. But there's a good argument that a keyboard driven UX is faster than a mouse driven one since you can input things so much faster than with a mouse.
I personally hate SystemD also, but that's more because it makes it such a pain to stuff like look at logs. I never remember the correct journalctl command. Just let me cat/tail a file like everything else. I don't know anyone who hates SystemD because it allows GUI configuration. It's just that SystemD made some other changes also that people don't like.
These businesses have no interest in trying to develop a desktop UI when Mac OS and Windows work fine already and someone else is doing all the work for it already.