The public TLS PKI was never supposed to serve every use case and you know it. But let me point out when it was possible to get a public CA certificate for an XMPP server with SRVname and xmppAddr:

  Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 1096750 (0x10bc2e)
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: C = IL, O = StartCom Ltd., OU = Secure Digital Certificate Signing, CN = StartCom Class 1 Primary Intermediate Server CA
        Validity
            Not Before: May 27 16:16:59 2015 GMT
            Not After : May 28 12:34:54 2016 GMT
        Subject: C = DE, CN = chat.yax.im, emailAddress = hostmaster@yax.im
        X509v3 extensions:
            X509v3 Subject Alternative Name: 
                DNS:chat.yax.im, DNS:yax.im, xmppAddr:chat.yax.im, dnsSRV:chat.yax.im, xmppAddr:yax.im, dnsSRV:yax.im

Ironically, this was the last server certificate I obtained pre-LetsEncrypt.