I was hanging around with some Roller Derby players around 2005. It was the days of MySpace and such, right? And I was heavily into that, and I made a lot of friends on MySpace, and then I was sort of intimidated when one of the rollergirls expressed her naked hatred for men who "collect women on the Internet like so many fucking butterflies". Anyway, there was a man and wife I was chatting with, and I mentioned MySpace, and the man said "why should I use MySpace and social media? Why?" and I launched into some optimistic explanation, and he interrupted me to shout "it's just to get spammed! They are just going to spam us!" and I paused and said, well, yes, that's true.
So I think that is the fundamental purpose of social media platforms: you're signing up to be spammed. Any pretense of keeping up with friends, family or the news headlines is a flimsy excuse. You're going to get spammed, by hook or by crook, and the sky's the limit.