Thread:Meighan/@comment-2190376-20120204181801/@comment-26686429-20120205143705

Yes, it breaks the ToU: "Not intentionally block, remove, or otherwise obstruct the proper functioning and view of advertisements, and/or user interface and functionality by other users, including but not limited to changing or adding javascript or CSS changes to the Service that would prevent the proper display or function of advertisements and/or user interface and functionality."

There's nothing to stop people creating new wikis, nor establishing your wiki as the dominant one - using CSS to hide other people's wikis is abusing your position as the dominant wiki about the subject to create the illusion that you are the only one.