I respectfully disagree. The dislike button definitely had value. You cannot read 10,000 comments on a video with 1.5 million views. Like/Dislike ratio was a fast way to ascertain quality. Maybe it was incorrect 20% of the time (and I'm being generous there), but even that means that it was helpful 80% of the time.

And according to your logic, the Like button is also useless and should be deleted as well, since you can equally have a mob of people hitting it without really "liking" the video. The same is true of the comments.