"Should every nostrich run a relay?" is a very different question from "should every Bitcoiner run a Bitcoin/lightning node?" due to the differences in guarantees.

I think every nostrich should run a relay IF THEY REQUIRE PERMANENCE for their historical notes. What do I mean by this?

Relays should be considered ephemeral. They are under no obligation to store your data indefinitely unless you enter into an agreement for that (paid relays.) Relays can go offline at any time and take your notes with them. This is why clients connect to many relays by default, for redundancy.

I run a relay for myself that only accepts notes from my pubkey. If my third party relays change, I'll just push my old notes from my personal relay to new relays for them to be indexed.

Nostr can't scale from the perspective of expecting every nostr client to connect to thousands or millions of personal relays simultaneously.