[shaggy]

Yes it is and has been for a long time. What this article really boils down to is a terribly poor understanding of how DNS works and why certain records are use for certain serivces. A CNAME doesn't "redirect" anything at any level outside of a resolver. In the case of www.example.com and example.com you use a web server to achieve the desired result. Even then it's not a redirect, it's a replacement the resolver determines the record is a CNAME, inserts the value the CNAME points to, then resolves the A record. In the case of the MX record for a domain a CNAME is a problem because in the absence of a MX record, the A RR record is used, in this case a CNAME. Would protocol specific SRV records be better? Yes, but since that change isn't happening quickly do what's right now and change in the future.