Because there is only one alternative (Xorg/X11), and it’s pretty outdated and not really maintained anymore.

For now it’s probably still fine, but in a couple of years everything will probably use Wayland.

Wayland has better support for some newer in-demand features, like multiple monitors, very high resolutions, and scaling. It's also carrying less technical debt around, and has more people actively working on it. However, it still has issues with nvidia video cards, and there are still a few pieces of uncommon software that won't work with it.

The only alternative is X. Its main advantage over Wayland is network transparency (essentially it can be its own remote client/server system), which is important for some use cases. And it has no particular issues with nvidia. However, it's essentially in maintenance mode—bugs are patched, but no new features are being added—and the code is old and crufty.

If you want the network transparency, have an nvidia card (for now), or want to use one of the rare pieces of software that doesn't work with Wayland/XWayland, use X. Otherwise, use whatever your distro provides, which is Wayland for most of the large newbie-friendly distros.

It's... complicated. Wayland is the heir apparent to Xorg. Xorg is a fork of an older XFree86 which is based on the X11 standard.

X11 goes back... a long time. It's been both a blessing and a liability at times. The architecture dates back to a time of multi-user systems and thin clients. It also pre-dates GPUs. Xorg has been updating and modernizing it for decades but there's only so much you can do while maintaining backward compatibility. So the question arose: fix X or create something new? Most of the devs opted for the later, to start from scratch with a replacement.

I think they bit off a bit more than they could chew, and they seemed to think they could push around the likes of nvidia. So it's been a bumpy road and will likely continue to be a bit bumpy for a bit. But eventually things will move over.

Because the older alternatives are hacky, laggy, buggy, and quite fundamentally insecure. X.Org's whole architecture is a mess, you practically have to go around the damn thing to work it (GLX). It should've been killed in 2005 when desktop compositing was starting to grow, but the FOSS community has a way with not updating standards fast enough.

Hell, that's kinda the reason OpenGL died a slow death, GL3 had it released properly would've changed everything

Wayland vs Xorg is mostly equivalent to a beat up 80's car compared to a brand new car.