I don’t think caching and syncing has improved in 18 months. I don’t understand why that’s difficult is it because of how the relays our configured? If so, can they enforce if a relay is not configured properly then it will not be apart of the network.

It's closer to real life... Like in real life how many friends do you have? It depends on how and who you count in. Is that the person you chatted with once two years ago your friend?