IMO it's less about having an archive; more about being able to receive mail at that address. After all, email address is the root of your identity for basicall

IMO it's less about having an archive; more about being able to receive mail at that address. After all, email address is the root of your identity for basically everything on the web -- what's the plan if every account you have is @gmail.com and Google banishes you? Running it through your own domain means you just re-point it at a different provider and keep trucking.