Much later, when they switched to simple thumbs up/down, the recommender system was entirely useless to me. (Not merely because of the dumbed-down rating system; the recommendations were genuinely bad.)
For the time in between, I'm not sure if the degradation was gradual, sporadic, or not degraded at all.
I still think recommender engines should always enable some form of user tuning. If it doesn’t, then the recommender is a tool for services to control your behavior rather than the other way around.
Although even before I started listening to Spotify while working etc, it seemed to have run out of things to recommend. My weekly discover playlist would be half things I’d already liked. So...who knows. But I miss the discovery functionality quite a bit.
Nothing really beats the recommendations of a human curator with exquisite taste, and just listening to new music nonstop and plucking out the gems as you go.
It's also easy to theorize about "big media" controlling what I listen to, so I still feel the need to do my own exploring, even when I'm getting recommended good fresh stuff.
Similarly, if I play Blacklist in the background as basically noise, I don’t want to see a bunch of related shows. I guess I could give it a thumbs down but I only do that for actually terrible movies.
Also Spotify and Apple music seem to have okay recommendations
Netflix doesn't show IMDB scores, so I have to check it always independently...it sucks.
That or a ceding of recommendations to marketing. That feels too cynical, but more accurate.
Not a streaming service but Google's Discover news is also very good (probably the best recommendations I have come across).