Very much agreed that part of the problem relates to scale -- and, great analogy! It's an interesting thought experiment: if each school had an Lemmy instance, how would they work together to host communities and make it easy for people (in all the schools) to find the communities they're interested in? If they each had a Mastodon instance, how would they share blocklists? And so on.

And great point about the different dynamics between large instances and smaller / more focused instances. There's always a question of which communities an instance sees itself as in service to -- and similarly there's always a question of which instances and communities the team developing the software is in service to.