While the users expect all this fun stuff from parsing their data. The music industry is doing to use that to formulate the next set of earworms. And target folks with retail therapy options when they are weak. And goodness knows what else.
Just like AI feeding on itself, these algorithms shut off new music from autogenerated playlists I'm favor of boring things we know by heart. I suppose some folks like that, but I want new music from artists I have never heard of that I can experience. And TBH, for the costs of these subscriptions, you can make your own playlists with superior variety.