When you mention something like DHT, that means you're thinking of nostr as some kind of huge distributed database where data is guaranteed to be available for all time across all keys and easily searchable in a single query.  Nostr isn't trying to be that.  Saying nostr or gossip won't scale is like saying RSS won't scale, or IRC won't scale, or Usenet won't scale.  Yet, they scaled just fine.

Give up on the twitter style mega sharded database idea.  Give up on easy centralized indexing/searching or thinking you'll connect to one firehose of data to rule them all.. it ain't happening.  But you already know that.. I guess it's just I'm surprised at the expectations is all.  If I wanted to find someone on nostr, I'd just connect to their relay and run a single query, I would know where to find them from their nip05 or from their last known relay list, or from any number of other out of band sources.  EZ. 

 Nice analogy wit the RSS feeds sir.