Yes to both.
Initial load of all the follow lists is just heavy. Need to use graph snapshots instead, at least on web & mobile, so there's that centralization. But you can always locally recrawl when you feel bandwidth-rich.
Discussion
Negentropy or "send only matching event ids, I'll request those that I don't already have" would help with bandwidth
This is why i propose, aside from all the other stuff you can use, to also start creating musig handshake events. Still need to do the write up, and i have a rather specific usecase in mind, but:
nostr:nevent1qqsxxwykxh452jw007kv5gpjr9lzp24ajylqhyhy9meyva3t3fkp6vqx4q424
Oh sorry, missed the bitchat context, nvm