In a more perfect world, we could blithely assume domain registration gives one ownership outright, and that it obviates the need for forwarding. But such is not always the case.

Reading the fine print on some registration/hosting sites, it appears that with many, you only hold title (as it were) to the domain name as long as you're a client of theirs--if you switch reg. agents, you may lose the ability to continue using that domain name with another agent. There may be a hefty charge to transfer the domain name, or the original agent might not even allow a transfer.

Domain names actually map to repositories rather than bare IP addresses (after all, you can never be sure which server--or servers--your host keeps your files on at any time.) But your point is taken: URL translation and reverse-translation ought to occur invisibly and automatically with a properly registered domain name. The question is, which reg. agents play by the rules, rather than fronting proprietary hosting services?

(We can sidestep the issue of URL translation when multiple domains share resources on a single site--not a concern for me.)