I don't think it's possible to draw conclusions from one's own experience with youtube recommendations and extrapolate it to others or to any sort of judgement about the quality of the algorithms. We are simply not privy to what, exactly, youtube is doing.

I think it's wise to heed Guillaume Chaslot's warnings. In the same way that youtube exploited (inadvertently or not) glitches in the brains of preschoolers (remember "Spiderman and Heidi" videos? if not, don't look it up). There's reason to believe these things can fly under our radar and influence adults in ways that are not perceptible and not something we would approve of in advance.