I think it’s just not having critical mass.

It’s definitely a huge part of the issue. Also demographics. The techy slant the Fediverse has does not seem to have a huge overlap with sports. That’s why I can mostly survive on Lemmy when it comes to Formula 1 discussion (although it’s still sparsely populated) while football (soccer) is much less active here.

how come the fediverse has attracted a grand total of zero e-sports people?

Hey, I post discussion threads for The International (Dota 2) every year, and usually get some replies and discussions in them too! I would say it’s even somewhat close to the activity level football (soccer) sees, though less than F1.

But in general I think Esports is just less popular overall than regular sports, so that’s your answer.