Huh. It's certainly an interesting idea! Strictly speaking, individual people could implement this today, since nonstandard HTTP verbs don't break anything that doesn't know to request with them. (It wouldn't be of much use, because clients wouldn't know to use it, but still -- something that could easily be prototyped).

I don't think FAAANG (or any other big players) would have much interest in making it happen in the standard though, since it would undercut their big-player advantage.