"Esports" games require absolutely massive communities (e.g., marketing) and no open-source game has even come close to the scale required to sustain an esport.
Servers can be community-run and centralized per league/community. See TF2 (more decentralized) and FaceIt (Counter-Strike) for examples of self-moderating communities than can exist outside of the developer-centralized model.
At no point do I assume P2P to be a requirement or even beneficial in this scenario.
As for FaceIt, that came about from the existing CS community. After 15+ years of the game being out. You can't just build something like that in a vacuum.
The whole point is that "esports" depends on centralized servers and somebody footing the bill for that. Even in fighting games that are P2P, there's still the matchmaking lobbies.
And you could say "well, there's FightCade!"...but a) that's illegal and b) I've never seen more than 150 people in a FightCade lobby and it's usually around 10-30. Esports games have > 10^4 concurrent players.
Your argument sounds to me analogous to “everybody will just use Twitter/X because why would somebody want to pay to host a Mastodon instance with no participants.”
The reality is that some (but not all) people do genuinely have grief with the centralized platform (moderation, censorship, toxicity), do have the ability to pay for something better (or freeload off people who do care), and are thus willing to make a change with there’s sufficiently low resistance.
The reason this is possible at all is because people that did care in a very small minority made the decentralized platform for free while everybody else was oblivious. It doesn’t get built overnight and usage doesn’t convert overnight, but when the solution exists it can then be viable.
I do think open source games are a fair ways off, but I find it impossible to believe that people will work for decades for free on open source social media because they enjoy it, but the same will never be true of games.
It’s an eventuality, and it is one that changes dynamics for the end-consumer.
Perfect example. With the existence of a sufficiently-close open-source base, the community would have self-organized TF2 out of existence with a functional replacement. This just isn’t possible today, but when it is possible there will be no turning back.
If by "sustain an esport" you mean as a profitable enterprise, then probably not. Is that the best metric though? Open source games can become popular enough for competitive scenes to emerge; Warsow is an example of this.
Popular enough for competitive play but not enough to get corporate sponsors seems fine to me. It's probably not healthy to be promoting the idea (to kids particularly) that playing video games can be a profitable career.
For it to be an actual contest it needs an actual sample size of players. Sports need spectators and narratives that generate interest.
Nobody gives a damn about Warsow the same way nobody gave a damn about Ferret-Legging.
It's not a sport if its players are limited to "you and your mates from round the way", that's just a game. Sports are meant to expose the limits of human potential.