Most web sites sit behind load balancers and stateful firewalls. They have many, many opportunities to do the port translation to make $name and www.$name work

Most web sites sit behind load balancers and stateful firewalls. They have many, many opportunities to do the port translation to make $name and www.$name work the same way. The theory you espouse, that www was the only viable option to move web service to a new machine, was true in the 90s when we started doing this. That's how the practice came about. It's 2011. It's not an issue anymore.