But the WoW bot was interacting with Blizzards servers and sending changeable actions that could affect the state of their servers. It feels like there's much more to this then a simple TOS.
More important is that it's designed to interact with blizzards servers. Adblock is a generic utility
Different Adblockers work in different ways, some block based on size/shape of images (IAB standards) but the most prevalent method is regex'd URL identification to known ad+tracking sites.
True, but the sites it's working against aren't the content providers, just the advertisers. As such, it's not intending to help you violate anyone's TOS in particular (except maybe and advertiser).
It was a local app, not remote. Even if I concende that it was remote, what about a wallhack for counterstrike? Should that be legal since it has zero server effect?