I think this business of a roving IP address is a distraction. In my own case, for example, I post from home via a Virginmedia allocated IP, my phone via a Vodafone allocated IP, and when I visit my sons I may post via their IP addresses, or via a hotel's. Then - until I retired at the end of Novemeber - I occasionally posted from several different sites at work, each with their own dedicated lines. So people can have quite complicated IP patterns without any intention of avoiding control.