> Other than to support non-TCP transports (like UDP), which I would assume are fairly uncommon,

 

This is actually something we leverage in production:

 

- TCP for server-to-server

- WebSocket for browser-to-server

- single HTTP/2 stream treated like TCP on shared HTTP/2 connection

 

The need to target both WebSockets and TCP was actually a very concrete initial reason for creating RSocket, since HTTP/2 framing is not exposed in browsers or most client/server APIs. More on this is found in the Motivations doc: https://github.com/rsocket/rsocket/blob/master/FAQ.md#why-not-http2