Comment by ThePhysicist

Simplicity is something that got completely lost in most (not all) modern Internet protocols. As an example you might look at QUIC & HTTP/3 and its many extensions. The IETF draft of the QUIC specification is already many times longer than the one for TCP, and then there are the many extensions like MASQUE, HTTP3-DATAGRAMS etc. that are themselves quite complex. This complexity makes it in turn quite hard to implement these protocols completely and correctly. For example, Cloudflare's official QUIC implementation still lacks support for TLS key updates, which leads to QUIC connections simply timing out after the server requests a key update. So if you use a quic-go QUIC server and a QUICHE based client you're currently out of luck unless you patch the server to not perform any key updates (which is really bad for long-lived connections due to lack of forward secrecy).