They would claim the same things of their stack, with some reasonable validity.  I was doing single sign-on with PKI on the ActivityPub stack in 2007 (which extends to the whole semantic web, solid, DIDs, FOAF etc.).  Each system has trade-offs.  But I agree nostr has a special combination, particularly, payments.

Ultimately turing complete is turing complete.  All the stacks will end up as turing complete.  Identity is not sigular it's a key ring of relations.  Some are further ahead on this than others.  Some have politics and so on.

Like you, I'm very bullish on nostr use cases, as a form of advanced innovation.  However, other stacks have gone 10x in user base, which unlocks other things such as sustainability etc. though perhaps with added politics.