For what it's worth, most (all?) the comparisons in that phoronix article [1] compare the performance of apps running under XWayland (in a Wayland session) versus an Xorg session. That's because most steam games use SDL 2 which still uses XWayland by default (the default has been changed in SDL 3 though [2]).
So using the data from that article to conclude that "[Xorg] still generally outperforms Wayland" seems wrong. A comparison between native Wayland apps vs Xorg apps would have been a lot more relevant though.
[1] - https://www.phoronix.com/review/nvidia-510-wayland [2] - https://github.com/libsdl-org/SDL/pull/6362
When Wayland was proposed, it’s biggest benefit was for direct rendering. At the time AIGLX was still the main hack to getting decent compositing/GL performance and had some major drawbacks. Wayland was designed in a manner more similar to the DRs in other desktop OSes (Windows and OS X, primarily). But, in its long development and adoption period, X’s DRI/DRM infrastructure has had plenty of time to mature and many of those arguments have been made moot. In fact, it still generally outperforms Wayland in many cases:
https://www.phoronix.com/review/nvidia-510-wayland/2
Theoretically Wayland is still conceptually superior in that regard; but you’re right, it hasn’t shown the drastic improvement originally promised.