This is exactly the issue with all recommendation systems. It's silly when I look at Amazon and see 15 different cat water trays just because I got one for my cat a month ago - but when it comes to social media the effect is really poisonous. YouTube is a good example: if I listen to something about Roman history it's all Rome all the time - a much better recommendation would be to suggest Greek / Persian history - rather than pigeon-holing me after 1 or 2 videos.
I really think I would watch more videos if the recommendations -challenged- what I enjoyed, rather than couching me, but I have to assume that someone has run that experiment and ad revenue went down.