Right, and nostr.band could do it too (though their numbers would be different to Primal's). Chrome itself could do it if the Chrome team wanted. But this isn't a success of Nostr, in the same way Gmail gmail giving you 10GB of storage isn't a success of SMTP. You compare that to atproto, where the the equivalent of Primal's caching service is built in to the core protocol itself, and the difference becomes clearer. Or you look at bittorrent and how tit-for-tat incentives are core protocol, whereas for nostr relay monetisation is something strapped-on and not core protocol. Makes a difference what's in the protocol itself.