Good morning Fediverse.
I think I came across a good example, why ActivityPub C2S is bad. Consider wanting to display an actor profile. Like mine. You will probably want to display if you are already following me or not or well if you requested to follow me and I didn't react.
To do this with C2S is complicated. One can work around its limitations. However, that's homework to understand how C2S is awful. For this homework problem, please consider at least 2 clients. Second part, a client without permanent storage.
See cattle_grid#147 for how something that has processing capabilities can get around it.