Roasbeef proposes decoupling the onion messaging graph and the channel graph. afaik what we do now is send onion messages over the channel graph even though they aren't payments. Also, your ability to use some onion messaging features requires payment paths to your "contacts" upgrade else you need to connect directly to "contacts" or find new channel partners (which is expensive). Unless we intend to charge a sybil fee for non-payment onion messages, there's no reason we need to use the channel graph. I suspect these weren't decoupled sooner for that reason, but we also haven't seen sybil fees for non-payment messages emerge yet.
Roasbeef points out that there are many advantages to decoupling:
- separation, and independent evolution, of concerns/services
- onion messages won't compete with peer gossip and channel updates
- adoption can be low on the onion messaging overlay yet still serve its purpose better than overloading the channel graph (which is established without considering onion messaging features)
I like it - so long as it won't need payments for sybil resistance. On that point, it may be less sybil resistant because anyone DoSing you with onion messages now is a channel peer afaik and has something to lose.