I heard a third-hand rumor that when Netflix switched from 1-5 star ratings to thumbs up/down, they stopped even using your ratings to personalize recommendatio

I heard a third-hand rumor that when Netflix switched from 1-5 star ratings to thumbs up/down, they stopped even using your ratings to personalize recommendations. They were simply using watch time. I've since read someone else on HN say that is incorrect. There are old films I really like but have not streamed on Netflix. If I give them a thumbs up, it would be a pity of Netflix didn't take incorporate that data.