Wait, since when did X11 have a screen tearing problem?
Like yeah, if you're not running a compositor you're gonna get screen tearing unless you turn on TearFree, but a) hey native triple buffered everything! (except on Nvidia because Nvidia doesn't care) and b) all of that is moot if you do run a compositor. That said KWin on X11 has frame pacing issues so disabling its compositing to play games is a good idea. You don't have to do that on Wayland. Also c) games can totally do vsync themselves, can't they?
At least you CAN do xorg.conf stuff. With Wayland, if your DE doesn't provide you a scroll speed slider you're just fucked.
And about "security"... sure, if malicious apps on your system are even part of your threat model in the first place. It makes sense for phones. On desktop though, most malicious stuff is probably confined to your web browser anyway. I'd rather have working copy-paste and window control scripting and suchlike.
Sure they support both X11 and Wayland for NOW.
KDE soon won't, and that's the one we use.
Gnome I got no clue, we don't use Gnome.
Cinnamon is likely to be alright and supporting X for a good while.
Also like... "but that's not STANDARD!" is literally my entire point. That's the problem. "That's not a standard use case" being used as basically a "go fuck yourself, you don't matter". (You might not be implying this, but a lot of people sure do.)
Linux should support the weird stuff too. "That's not a standard use case" could be used to reject just about anything you don't like, even, say, custom fonts.