Does anyone here remember a site called Flixster back when they had a forum and everything? I stay away from social media except when I need it to contact someone but that's the only one I used outside of Facebook and it was really fun as a teen. You had your own page which was a bit like a cleaner version of a MySpace. I ended up having some really good conversations with some nice mormon girl from Utah, a guy from New Zealand, a college student in Halifax, and a girl with some social anxiety from Illinois. It was really easy to discover movies and see trailers on that site, they had a rating system out of 5 and it was easy to interact with folks. Shame it went down after RottenTomatoes bought it (or they bought RT) and closed up the social aspect of the site.
There's no proper social media movie site anymore, Letterboxd is the closest I guess. The imdb forum was truly awful for films, very disorganized. You can still use the RateYourMusic film forum or a couple Reddit subs like Flicks or TrueFilm or the somewhat inactive Criticker forum.