Because the points system replaces online the offline signals you, and we all, use for just that non-thinking - signals like facial disgust, like if a restaurant is full or empty, like other people in a room taking notice of one person.

we need social signals to determine how the society we are in is functioning. points, likes, follows are very poor proxies - but we need something. if those proxies are making billions for some people that's not the fault of our need for social alignment.

Or maybe the "signals" are thoughtful responses to comments...