even nostr seems to want bubbles, under Why not just use Mastodon/Fediverse? they write:

> The most interesting feature of Mastodon is that by its nature it creates communities with shared values that grow in each of its servers. Or, should I say, that should be a feature if it actually worked like that. In fact these are not really communities, but a mashup of users that may share some interests among each other, but also have other interests and those other interests end up polluting the supposed "community" with things that do not interest the other users.

ie. they're complaining that federated communities are too diverse and multi-faceted, instead of being divided into nice little laser-focused grids of shared interests

I think you're misinterpreting this statement. I'm using nostr for more than a year and I can publish to any free relay I want to. On Mastodon your account is tied to a specific instance while on nostr you have a private/public key pair that's independent of any relay. There are some more focused/curated relays that have additional filters/rules or only allow certain people to publish (whitelisted public keys, often paid or invite only). I know of no mechanism on nostr that would force anyone to stick to certain topics or issues.

I think the point of the quote is that Mastodon tries to be both a topic-centered community platform as well as a "everything goes" public social network like Twitter/X but the federation aspect is not true decentralization because you can easily lose your social graph/reach if some instance admin doesn't like you or your own instance gets #fediblocked.