Say you have an account that you post from for a few years, and then you get banned. Then say you move down the street and get a new IP address. Or, say you only sign into the new account from another IP address that you have wireless access to. Do the mods just go with the probability that it's just you on another IP address? What if they were actually banning the innocent guy down the street who happens to be the nicest guy in the world? That would be awful. Perhaps too awful to lead to an assumption.
I mean imagine if that's how murder trials worked. Like if you just send guys to the electric chair just because they're probably guilty.