[tobiasSoftware]

The dislike button is extremely useful to indicate scams and erroneous information.

Even outside of outright scams its still useful. For example, there's a Numberphile video (a high quality channel that explains math to ordinary people) where they go off the rails and make a bunch of errors to claim that the sum of 1 to infinity is -1/12. It's based on real concepts but the way they present it is completely incorrect. It had a dislike ratio of 20% whereas most of their videos have a dislike ratio of about 1%. By seeing such a high number of dislikes, it alerts the user that something could be off about this video and that they should not take what is said at face value.