The "U" doesn't stand for Unreliable. It's basically the simplest possible packetization that doesn't offer much of anything that the underlying IPv4/IPv6 layer

The "U" doesn't stand for Unreliable. It's basically the simplest possible packetization that doesn't offer much of anything that the underlying IPv4/IPv6 layer doesn't, besides filtering out packets based on port numbers. It's very commonly used for games and video services, where applications can recover from the odd dropped or out-of-order packet. As the sibling comment mentions, what does "It's been decades?" supposed to imply? It's also been decades since TCP was invented, are you calling for its discontinuation too?