Another interesting protocol, perhaps underused, is SCTP. It fixes many issues with TCP, in particular it has reliable datagrams with multiplexing and avoiding head-of-line blocking. I believe QUIC is supposed to be faster at connection (re)estabishment. https://en.wikipedia.org/wiki/Stream_Control_Transmission_Pr...
SCTP is a superior protocol, but it isn't implemented in many routers or firewalls. As long as Comcast / Verizon routers don't support it, no one will use it. It may be built on top of IP, but TCP / UDP levels are important for NAT and such. Too few people use DMZ and other features of routers / firewalls. Its way easier to just put up with TCP / UDP issues to stay compatible with most home setups.
https://www.ietf.org/proceedings/48/I-D/sigtran-sctptunnel-0...