Small correction: while it’s true that the client<->server exchange is secure, this doesn’t matter because ANY client can request a certificate for any DNS addr

Small correction: while it’s true that the client<->server exchange is secure, this doesn’t matter because ANY client can request a certificate for any DNS address. It is no extra security, because an attacker can just submit their own request for the same domain from a different client that they control. It only needs to be secure to prevent MITMing the token. The key to LE security is to check the record from a bunch of servers with diverse paths to the nameserver, so that any particular intermediate ISP cannot spoof the DNS/TCP to all of them. Ideally these paths would be direct, but that’s not feasible, since the requesting server could theoretically be hosted anywhere. I guess they are also more likely to implement the recommended DNS security extensions than a (likely) out-of-date resolver in a consumer router.