But this wouldn't give you two-way interactivity, and RSS and ATOM are just different ways to go about representing RDF.
I could entertain the argument that we don't need two way interactivity, and that most of the applications would be fine by implementing their own ad-hoc API. This is exactly what is happening in the Fediverse now, where every microblogging project ends up implementing Mastodon's API and every Lemmy client goes straight up to Lemmy's API instead of getting the data from "raw" ActivityPub.
I could entertain the argument that we don't need two way interactivity, and that most of the applications would be fine by implementing their own ad-hoc API. This is exactly what is happening in the Fediverse now, where every microblogging project ends up implementing Mastodon's API and every Lemmy client goes straight up to Lemmy's API instead of getting the data from "raw" ActivityPub.