To be honest, one part is what everyone mentioned here. Not being preinstalled and all that.

The other part is that unfortunately at least according to my own expirence as a Linux noob a few years ago some Linux communities can be very toxic. If you're asking questions of how to do X and someone comes along and is all "why do you even want to do X if you could also do Y? Which is something entirely different but also does something vaguely similar"

That's one if the things.

And then other curiosities. I cannot for example for the life of me get my main monitor to work under Linux with any new Kernel version. My Laptop just refuses to output to it or the second monitor attached via Display port daisychaining. On the older version it works, on the newer it's broken. I have tried troubleshooting this problem for over half a year and it's still broken. And that's out of the Box on Ubuntu LTS...

So i don't really understand this question. There are major roadblocks. With Wayland which is default for Ubuntu now those roadblock jist became bigger. Screensharing in multiple Apps including slack is outright broken unless you use the shitty webapp. The main player Office 365 largely doesn't work at all on Linux. All these things that should work for a Desktop operating System don't work out of the Box as they should.

That's why people aren't using it and companies aren't preinstalling it.