I'd argue that the "rampant cynicism and nihilism" and more a result of the environment than algorithms manipulating people, the content is also made by other people, and it just serves up what people want. Your feed is often just a reflection of what you're feeling since everyone has their own feed instead of the reddit or HN approach with a shared feed. Also the phrase is that a few bad apples spoil the batch, nobody cares about the rest of the batch until you can get rid of the bad ones
I'm much more a descriptivist than prescriptivist so if there's a pattern among people I'm inclined to think it's a true issue instead of people just thinking "wrong" en-masse