Because people are actually using this as a community now and there's a desire to not just open the floodgates before all the moderation pieces etc are in place. I joined when it was roughly 15-20k users and each wave of invites brought distinct subgroups. Then, the original short invite code tokens began getting brute forced and there was a large wave that completely disrupted the balance of things.

There's the protocol, but then there's also the community – and communities are ecosystems not just technical problems.