"Christine that's ridiculous, we're not expecting a million self-hosted users"
Well I think it would be nice!
But regardless, ActivityPub has 27,000 servers on it, all meaningfully participating in the network.
ATProto, in its current design, would be crushed to DEATH
"But Christine", you may say, "I heard gossip might fix this!"
No. It cannot.
In fact, I was being more generous than a gossip network, and assumed you only *received* a message once.
With gossip you might *receive* more than once.
But you need to receive a message to know it.