It’s definitely an interesting and relevant idea I think! A major flaw here is the lack of ability for communities to establish themselves as discrete spaces desperate from the doomscrolling crowd.
A problem with the fediverse on the whole IMO, as community building is IMO what it should be focusing on.
Generally decentralisation makes things like this difficult, AFAIU. Lemmy has things like private and local only communities in the works that will get you there. But then discovery becomes a problem which probably requires some additional features too.