Netflix now has much better sources of information than the self-reported star ratings.
Self-reported ratings fail in a lot of ways. Users can upvote what they think they're supposed to upvote. They'll downvote something, then go watch the sequel, because "It's terrible but I love it". And since they're seeking out stuff that they suspect they're going to like, they either compress all of the ratings into the top tier, or they end up "hating" things that they actually thought were merely so-so.
I suspect that even the up-down ratings get little attention in their recommendation engine. They have far more information, especially in the streaming service. Did you watch all of it? Did you watch it all at once? Did you watch it more than once? Did you watch it immediately after discovering it?
That's all stuff that users can't fake or be confused about. You don't get users saying, "Citizen Kane is the greatest film of all time, but I really don't want to see it." It's more likely that you can tease out what it is that a user actually wants to see, rather than what they tell you they want.
Netflix did run a competition back in the DVD days, when they had less interaction with the user. They did get a slight improvement, but at about the same time, they introduced streaming, and a whole lot of Big Data techniques appeared that could take advantage of that new data.
So it wouldn't surprise me if the up/down buttons were completely ignored by the recommendation engine. Maybe it's just a reminder to you: "Oh, yeah, I did see that. It sucked."
The new system clearly misses some things, but a lot of the problem is that the DVD catalog is immense and full of classics, but the streaming catalog is weak and full of crap. The whole thing may be back-ported into the DVD recommendation engine, but that's the redheaded stepchild at Netflix these days. They tried to spin it off entirely.