TCP and UDP aren't the perfect solutions [for everything] and there's no shortage of proposed alternatives to TCP; Besides already mentioned QUIC, there's Curve

TCP and UDP aren't the perfect solutions [for everything] and there's no shortage of proposed alternatives to TCP; Besides already mentioned QUIC, there's CurveCP (https://curvecp.org/ https://curvecp.org/), MinimaLT (https://www.ethos-os.org/ https://www.ethos-os.org/), or even more extreme Named Data Networking (http://named-data.net http://named-data.net). For a background on why TCP is this way, look up "The Design Philosophy of the DARPA Internet Protocols", by David D. Clark, however knowing is little comfort.