Linux has been 'ready for the desktop' for more than a decade, far longer for those who use it 'professionally' so that old trope can be put to pasture. As to what to run on a Linux tablet there's Plasma Mobile (KDE), Ubuntu Touch, Gnome/Phosh, PostmarketOS with any of the above and more. If you're looking for a single 'Linux tablet interface' you won't find it as there is no single 'Linux $thing' anywhere - you get the choice between many alternatives, some more polished/functional/useable than others.
Complete disagree. Even today they are still trying to get simple stuff like smooth mouse support working, not to mention random crashes of the desktop due to proprietary driver bugs. Every single pro Linux person always claims their desktop works great. Well good for you. You ain't convincing the mass market anytime soon because Linux is NOT at their standard yet. Even if the powers that be manage to completely lock down computing and we lose the war against general computation, people will still not use Linux.
It would be more than easy to write the exact same comment about MacOS, iOS, iPadOS, Windows $version and whatnot. From the dreadful state of the MacOS window manager via the randomly disconnecting 'magic' touchpad to the myriad of annoyances in Windows - which used to crash when you looked at it the wrong way but that problem has been mostly fixed - to the lobotomised experience of running iPadOS to the fancily decorated jail which is iOS which has the nasty tendency to crash and burn when iMessage receives something it doesn't like or the iDevice which needed to be held just so to receive a signal, need I continue? In reality:
- mouse support under Linux was a fait accompli on the first device I installed XFree86 on back in 1993, That was back in the time of serial mice with DB9 RS-232 connectors, more than 30 years ago. What you call 'smooth mouse support' is rather vague, if you mean acceleration and the likes that has been around almost as long. Want to use a mouse/trackpad/trackball/trackpoint/whatever with Linux? Plug it in and it will probably work just fine.
- proprietary drivers are the exception to the rule that Linux is free software. One well-known exception here is nVidia which still rides the fence. While this is far less than ideal the drivers they produce are not known for producing 'random crashes'. Random crashes in Linux-land tend to be related to hardware problems and would crash other operating systems as well.
- the 'mass market' does not need convincing to use Linux since they use it daily, mostly without knowing they do so. Most of them don't use it on 'the desktop' (well, those running Chromebooks do but they mostly don't know about it) but there is nothing really keeping them from doing so.
You're living in a fantasy where 'the desktop' is an ivory tower where only the anointed incorporated entities are welcomed. This has never been the case and that will remain true as long as the hardware is (or can be made to be) open. Go ahead and install a distribution, I suspect you'll be surprised just how 'ready' Linux is for the desktop unless you insist on it being a 1-on-1 clone of Windows or MacOS and insist on everything working exactly like those systems. It isn't and it doesn't, things works differently between those systems and between Linux distributions. Choose one which comes closest to your expectations - probably Gnome-based if you're in the Apple world, Mate or KDE-based if you're used to Windows - and give it a try. If you want to do so, that is. If you don't want to try it that's fine as well. In that case I do wonder where your adamant statements about 'smooth mouse support' and 'random crashes' come from though.
