Why does every host offer a plan that scales at the same rate in every column (CPU, RAM, Disk space, bytes/month)? I can think of almost no application which requires lots of all of these. Why isn't there a host which allows you to scale your own requirements? Is it a technical thing, or just another form of "oversell and underprovision because most people won't use their plan"?
So I wouldn't call it a technical thing, but more of a strategic decision in how you want to position your company + offering.