This makes me think of how steam does indeed have some smarts to warn users when a game may be getting review brigaded. I think it's a combination of volume of reviews by time, and perhaps the referrer (?). It does seem to work fairly well afaict.
Not giving users this information and removing like dislike counts just makes it so that a small number of people at YouTube have even more ability to control what is pushed on that site. With this change users have even less ability to check the validity of a video; validity means different things to different users here. People who stay at YouTube will just have to deal with the fact that they will have videos pushed to their screen for reasons that are hidden to them, that they don't have the ability to check out anything other people think about the video, and can't even signal that there is something wrong to them about the video (sure, they could comment, but any comment can be deleted by the video author and there is the fear of losing your Google account, which can include their email contact to everyone and authentication information also, which can have huge consequences for their ordinary life).