Here’s an example of why you shouldn’t rely on only one relay. Club Orange was using only the Primal relay, and for the longest time their profile wasn’t showing up correctly. I kept wondering where they went, since I used to see them posting notes often. Instead, I kept seeing this strange profile with no picture or information. I thought, How did this spam profile get into my network? I couldn’t see any details and had no idea who it was.
Eventually, I took the time to investigate further and realized it was actually the Club Orange profile. I told them about the issue, they added more relays, and now I can see their full profile properly.
I really wish relays were “smart” instead of “dumb”—able to communicate with each other and sync our notes across relays. That way, we’d only need to add one main relay instead of many.
Unfortunately, that’s not how Nostr works, so we have to add multiple relays. It’s annoying, but necessary.

#relays