Until Google realizes you're using the capability to hide advertising and disables the feature to create a "trusted client" (trusted by Google to render their ads faithfully). They've pitched the idea before as a way to force users into Chrome from the server-side.

I'll go back to shouting at clouds now... Sorry.

Some pages seem to randomize element IDs to prevent adblockers from doing their job; randomizing CSS class names wouldn't be out of the ordinary.