You still need privileged ports to ensure that the right service binds the port. SRV records are great because I can run on any port but if any compromised proc

You still need privileged ports to ensure that the right service binds the port. SRV records are great because I can run on any port but if any compromised process on the system can bind that port you have greatly increased your attack surface. This can maybe be mitigated by dynamically updating the SRV record but that adds complexity and has caching issues.