Player numbers?

[Thurmnmurmn]

Except that didn't work most of Endwalker, where players kept going "Look at the Steam numbers, the game is dying!" just for statements from SE to come out showing that FFXIV was the one area of solid growth for them.

That wasn't what happened. People were cherry picking a small period of time post patch as proof of the game dying. Others actually also used steam numbers to show an overall growth over time to counter "the game is dying" threads.
Steam numbers can be used to see trends but yeah, serve nothing when it comes to knowing the overall count.

I agree with your last point. As long as there's enough people to play with, who cares how many more there are.