Nobody wants to keep working on X11, its design is fundamentally mismatched with the needs of a modern graphics stack and it contains a ton of legacy code and layers that make development difficult.
Check the lwn.net archives for some articles that explain this in detail.
The X11 DRI3 buffer swap mechanism is identical to the one used in Wayland. The fact that Wayland has still worse performance across the board (especially latency metrics) might be an indicator that Wayland is fundamentally mismatched with the needs of a modern graphics stack.
You are basing your conclusions on a single blogpost. Measurements from other people show that X11 wins in some cases, Wayland wins in other cases, there isn't a clear winner.
> X11 wins in some cases, Wayland wins in other cases
Even according to your blog post uncomposited X11 wins in all cases (or is tied within the error of one millisecond). It especially sweeps the floor with immediate rendering.
Uncomposited anything is madness in 2024. You have the VRAM, use it and save your battery life / power which is arguably far more important. It being tear-free is a very nice bonus on top of the power savings too.
(And no, composition is not just for 3D cube effects or anything like that. Although it certainly enables them.)
MacOS have moved on, Windows have moved on, Linux should do the same.
Check the lwn.net archives for some articles that explain this in detail.