Anyone can have an opinion and that's fine.
They DO ban accounts based on sharing an offending IP, though.It happened to me, and there are quite a few other reports in the ban section.
It could be not their usual method, or be related to gold selling or just manual investigation. I dunno why they do that a few times and not in most cases.
I wish I had the same opinion of other posters that they don't IP ban,as that would mean I'd still have my main account. (Never botted on it, used a different PC, different MAC, WOW install....you know the deal.)