Community grouping is also so closely aligned with a federated mindset - one instance may disappear but the community survives.
That said it’s clear you’ve got anything from openly fascist to diehard tankie on Lemmy servers so would definitely have to be a two-way choice and there’s a risk it just won’t work in the way we hope - I can easily see common topics fragmenting into so many shards anyway as one group can’t stand another group.