Back In My Day

Downvote button still works. The counter just isn't visible.

I know. But whats the point of them not knowing it?

Yeah. I can see how you would say that.

I think the only thing it does now is affect the relative position of memes in the Hot stream in some way (though I'm not sure of that formula), and also affects the relative position of comments in a thread. So even though you can't see the downvotes, you can still see the effects, to some degree.