Sure, even when outer loss is pretty close to zero, it's conceptually not great. On the other hand, I get 400mbps over TCP-over-TCP connections, and can't conn

Sure, even when outer loss is pretty close to zero, it's conceptually not great. On the other hand, I get 400mbps over TCP-over-TCP connections, and can't connect in any other reasonable way. 400mbps > 0. Even tunneling in UDP is not great due to MTU effects.