And the non-xwayland numbers are all within a single ms of each other.
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Not to undermine the measurements of the author (agree with you, it's a cool effort), but my read is that this was basically proof that it doesn't matter.
The saying we have in bike racing marginal gains is "leave no stone unturned, but turn over the big ones first"
So sure, first make sure your internet connection is solid. Then make sure your hardware and game settings are optimizing FPS to a reasonable point of diminishing returns.
Then make sure you don't use XWayland
Imagine a game that's just a pistol duel. When the kerchief hits the ground, players press a button, first person to press the button wins.
In an ideal world, with no delay whatsover, the probability P(A) of player A shooting no later than player B is 100 (because both players shoot at exactly the same time). If we add 5 ms of delay to player A, then P(A) = 0 (he will always lose). If then we add 50 ms of network latency to both players, P(A) = 0 still, because 55 > 50. If we instead make that 50ms delay 50ms +- 10ms (ignoring normal distribution for the moment, pretending every value in that range is equally likely), there's a 25% chance of player A experiencing an unwinnable delay (any network delay value > 55ms results in a value greater than player B's max of 60ms), resulting in a probability of P(A) = 75% * 50* = 38%.
If we make the network delay 50ms +- 5ms, then P(A) drops to 25%.
There are weird consequences of this, someone can shoot you after you duck behind a wall because you hadn't yet in their version of the game. An enemy moving left right repeatedly is likely vibrating in your version of the game faster than the rules of the game would otherwise allow. Etc. Ping matters, but it's not comparable to input latency. Input latency really does mean that you can click at the right time and miss your enemy. It really does delay how fast your camera spins when you move your mouse. Etc.