Well, TLS 0-RTT is only for resumptions, not a client’s first connection to a server. And the writeup in the parent post suggests requiring the server to enfor

Well, TLS 0-RTT is only for resumptions, not a client’s first connection to a server. And the writeup in the parent post suggests requiring the server to enforce atomic single-use resumption tickets, which would in fact get rid of replay attacks - at the cost of effectively prohibiting servers/CDNs from sharing tickets across multiple data centers, since then atomicity would require them to communicate (adding additional latency) before accepting each ticket.