The problem is that the number you see is pointless. There's a limited demographic who cares about the dislike numbers so much they go out and install a browser extension, which in then biases how they react to a video.

It's basically an echo chamber extension.

Not sure what you mean by "fight back", either. Google 100% could not care less if you install this extension. They aren't bringing it back unless the division's leadership has a change of heart on whatever internal goals they wanted to achieve by removing it.