Well, there's the fact that outrage seems to drive more activity than other types of content. YouTube sees it as a more profitable option to advertise a Very Angry Gamer(tm) to you, even if you aren't interested. I guess they assume that you'll find something to watch anyhow, but if they will profit even more of they can hook you into the outrage machine.

Then there's my personal hypothesis that in order to enable this, YouTube's algorithm weights your demographics, subscriptions, and viewing history much more heavily than your manual inputs.