I think I see what you mean - actors in ActivityPub as they are used in most instances nowadays, are just a way to avoid having to “subscribe” to everything coming from an instance. I.e. you use an actor to basically filter the messages you want from an instance so you only get certain messages, the messages from some specific actors.
Really makes me think how much simpler of a protocol that could be made if the protocol adopted the instance-based view from the start. Problem is network effects, as you say. You can’t connect to the fediverse as it is today unless you speak instance-based Mastodon-flavored ActivityPub. But what’s the path forward? I guess that’s been discussed plenty already without really reaching any conclusion other than:
- Agreeing on an “ActivityPub 2.0” seems hard-to-impossible.
- Migrating away from ActivityPub 1.0 seems hard-to-impossible.