Like with websites and password managers, rate limiting works fine when going via the expected auth service. Doesn't help at all when NSA/MSS/Mossad have popped

Like with websites and password managers, rate limiting works fine when going via the expected auth service. Doesn't help at all when NSA/MSS/Mossad have popped the contact hash database off Whispersystem's backend. (Admittedly, if that's your threat model, I hope you have enough magic amulet's in the submarine you now live in...)