this is because #fediverse is ignoring context. the implicit context is that `discoverable` means `http://joinmastodon.org/ns#discoverable` but they don't know that. so they can't actually handle the extension in its fullest form.
what AS2 calls out as "full support for extensions" requires being able to identify this equivalence and handle it. again, fedi does... let's call it "partial support".
the "implicit context" is now a hardcoded but unstated requirement of this "protocol".
25/?