The Banhammer of Loving Correction primarily falls upon people who make Dear Shitferbrains three times -- or in Spud The Truth's case, in two editions, but with three comments of overwhelming dumbth. Approved commenters who violate the Rules
generally get a warning, and if a comment is sufficiently egregious, it may get deleted. We only do IP bans of existing commenters following repeated and/or seriously dickish violations, and it's extremely rare.
Or if someone does something really stupid, like insisting that Applejack is Best Pony.