I agree with your overall point, but Wikipedia has a singular mission. Social settings can have wildy different missions from shitposting, to hobbies, study groups, to support groups, etc. There is no singular moderation ethos that can apply to all of them, that's why decentralization is important in social media.
We want to algorithms to work for the people, not have people slaving for the algorithms.
We're counting hypotheticals as real now? I suppose your not-hypothetical girlfriend goes to another school too, right? Just not motivated to visit?
As you're no doubt aware, the reason 99.9% of bluesky users are on a single server is obviously not because "nobody is motivated" to create other servers.
So like when bluesky starts having to pay back their investors I can portable my identity to.... one of the other equally populated blueskies out there?
BlueSky is centralized.