I rarely found insightful comments on Reddit. Good movie reviews are usually hard to find. Especially if you're looking for someone who at least gives a second thought to critical theory. I've run into thoughtful people here.

You're better off looking for as book club or something like that if you want engaging discussions. A lot of local community colleges are cheap and have courses for cinema or lit. Or, start that community here. There are some instances that don't even allow down votes, if you're looking for a positive experience. Don't let that last point derail, though.

Otherwise, maybe the broader thing you're talking about is the mono culture. The mono culture was gone long before Reddit shit the bed. There were no more tv shows that everyone watched then talked about around the water cooler. It's crazy to think about, but people were actually nuts about who shot jr. Like everyone wanted to know. It would be like your grandma knowing who mrbeast is and having an opinion about his shit ghost burgers and the drama around him trying to undercut franchises so he could get the rights back, or something.

Anyway, an active reddit community gave that feeling back. It was a nice warm hug when it worked. I can sympathize with the loss of that feeling. I'll add to what others have said here about rebuilding. Not only will we get back to that place, but it'll be better because there won't be some corporation owning everything with different goals.