Disclaimer: I have not looked carefully at the permissioned data proposal, but I know atproto reasonably well.

Stepping back for a momement, it's clear that permissioned data is driven by real world use-cases (Bluesky needs DMs, Tangled needs private repos, etc). However, I think the synergies with the existing atproto needs to be pretty significant to warrant developing yet another encrypted space spec. We already have various double ratchet protocols, Matrix is having a huge boom. From the point of view of an app developer, does everything need to be handled by atproto, or could we accept that atproto is just for the public stuff?