When these were social networks, I remember my friends and later myself too, changed our profiles to public, send requests to random strangers, messaged them to like our pictures. We were teenagers and we were competing on who's more famous by having a bigger number next to our friends list or likes. There was no influencer culture back then yet everyone was trying to be this new thing. There were rarely any influencer type features on these platforms.
So I won't blame facebook or Instagram for being what it is today, moving away from friends to social media stars. They saw what people were doing and only supported them. People did what people did.
I disagree with you. These companies employ PhD scientists who know exactly what they're doing to find and exploit the kinds of vulnerabilities you confess to along with ones you and I don't even remotely realize we have. It's not innocent by any means whatsoever.