This was a historical accident. I called my client "gossip" originally because I thought the name would appeal more to the females, and I thought getting a male user base would be easy so effort should be focused on seeking a female user base. I never did much else about making my client "girly" though.
Later on I found out that "gossip protocol" was a term of art already in use in the bitcoin community.
Since the gossip client was the first client to seek events from where people were posting them, instead of from a fixed set of relays, people started using the term "the gossip model" to mean "do what the gossip client does... which is to somehow find out where people post and read from those places."
Later on I wrote NIP-65 as a way that people could advertise in a more formal way what relays they will be writing their notes to (and where they can reliably read from). If you utilize someone elses NIP-65 kind 10002 event "write" relay, this is called the"outbox model" because they write to that relay as an outbox and you go pick stuff up from it. If you utilize someone elses NIP-65 kind 10002 event "read" relay, this is called the "inbox model" because you write there and can have some hope that they will be reading events that tag them from those relays.
Nostr is not p2p. If we had p2p, we would not need relay rendezvous.