No, it's not just auth:
That's why I built Budabit.club , the events are still signed and moderation is a good feature for communities.
- Communities can be interoperable
- Signed events mean forking groups is actually feasible, no other solution has this kind of guarantee.
- You can still keep other things open, and not exclusive: BudaBit keeps code collab features scoped to repo relays (even comments on issues etc) but you have the exclusive group to share things you want to actually be heard targeted to an audience that is there for a good reason.