I think users can definitely learn how to identify relays and deal with them, and I don't even think that will be painful, it will be a nice part of the experience. Users are already used to switching between different social media apps, document sharing apps, instant messaging apps and groups and subgroups inside the same app, or different functions and ways of sharing inside the same app

That is not a painful experience (although it is in some cases), no one has felt the need to write a good "aggregator app" that puts together all feeds from multiple platforms in the same app and hides the platforms so users don't even have to know their names.