Part of my frustration with #ActivityPub and one of the things I find baffling giving everything else in it: the lack of tools for backpressure.
Backpressure is fundamental in building reliable distributed systems (c.f., Notes on Distributed Systems for Young Bloods). From a C2S perspective I get why it wouldn't need to be specified, but from a S2S _federated_ protocol perspective its absence is frustrating.
All that it says is to take care not to overwhelm _others_ and a bit on rate limits