This is a great point and is also true of Facebook and a number of other platforms. Roger McNamee spoke at length about this issue with Sam Harris on his podcast back when it was called Making Sense. His point was essentially that the AI that controls the recommendations is trained to maximize clickthrough rates, and so it learns in its own way to feed us articles that make us angry, because we click and share more that way. Hence the tendency to lead people down rabbit holes of extremism.