Using tag indexes to easier pre-signal channels for notes makes sense. But it‘s also a bit schizophrenic, because it‘s harder to leave the beaten paths. And that‘s quite precisely „mainstream“.

I would guess that „#zapathon“ is not very useful for indexing. Date parts and pub keys probably build more useful pages.

On the other hand when I search Damus universe for a tag like „#ruby“, it could return much faster when the path is beaten.

Is nostr about feed or search? At least for me it‘s mostly feed (now).