It depends on the user. Some people may just want to play around posting notes, but many people will be more curious and may lose interest in Nostr if you don't explain how it works.

Also, the concepts of read / write relays are actually difficult to get your mind around. I've been developing using the protocol for a bit now, but I still need to go back and remember what these things mean. Explaining these can make for a fun conversation with a smart new user.