OK, I’m a bit confused. Which topic are we talking about? On the thread this one branched off from, you said;
So I’m commenting on AP forum<>forum federation in general, not just Lemmy<>Lemmy.
I understand this too, but it’s clearly not the reality. There’s been a lot of discussion here recently about why it isn’t and what ought to be done. Eg;
https://socialhub.activitypub.rocks/t/a-brief-and-unromantic-history-of-activitypub/
But in the specific case of forum<>forum federation, there are things smooth interop will need at the protocol level that are completely unnecessary in others kinds of AP apps. So they are better defined in a forum/ group FEP, or a set of them for different types of forums/groups. Laying out what a forum app needs to implement on top of vanilla AP to achieve a good UX.