He was arguing about 99.99% of users being people that cannot use your stuff because chrome doesn't allow the use of snakeoil / self signed certs for QUIC, specifically, and TLS encryption is mandatory.

If you compare that to the graceful Connection: Upgrade handshake in http/1.1 and websockets, for example, this would've been much better because there is no isolation based on tools and libraries, only based on trust chain of the certificates. If a new version of the protocol breaks, it automatically falls back with both parties knowing about it. If QUIC protocol has changes on the client side, good luck finding that out.