QUIC includes a standard for peer address discovery: https://www.ietf.org/archive/id/draft-ietf-quic-address-disc...

Wireguard doesn't, which is why tailscale took off so much, since it offers basically that at its core (with a bunch of auxiliary features on top).

Show me some wireguard discovery/relay servers if I'm wrong.

Also, QUIC is more language-agnostic. The canonical user-space implementation of wireguard is in Go, which can't really do C FFI bindings, and the abstractions are about dealing with "wireguard devices", not "a single dump pipe", so wireguards userspace library also makes it surprisingly difficult to implement this simple thing without also bringing a ton of baggage (like tun devices, gateways, ip address management, etc) along for the ride.

If you already have a robust wireguard setup, then of course you don't need this and can just use socat or whatever.