The excuse I have seen for removing the dislikes is because YouTube did not think the dislikes where genuine.
And that easy enough with some content.
Take forgotten weapons, get a notification video posted 2 minutes ago, click on it, say its a 15 minute long video.
Its been up 3 minutes by the time I hit play, but it already has a dozen dislikes.
Its like some dweeb actually wait for a post to hit the dislike icon.
Similar with other channels. Hell I have noticed it with the History guy too.