Look, if I'm a social media app developer, I'm going to look for something that offers me two things:
1. Network effect - something people actively use
2. Protocol and API stability - something that won't change due to someone else's whims
This means the Fediverse.
Once developers en masse start developing for a platform, that's when the fun starts.
The iPhone didn't get interesting until developers made apps for it.
Ditto with the web.
We haven't even scratched the full potential for ActivityPub.