Well that implies someone designed the movie business to be some kind of cultural binding agent. But its barely a century old and there are older mechanisms that bind groups together. Philospher Charles Taylors classic The Secular Age is worth checking out.

I would say moviegoing was at it's zenith in the US around Great Depression, and has been on a downhill slide ever since.

Here is a video showing the Palatial Landmark Theatre in Syracuse NY opened in 1928 (they don't make them like they used to): https://www.youtube.com/watch?v=GdCaX7WrpoI

Today the multiplexes are dying and the star system that put Harrison Ford on top has lost touch with the younger generation. The moviegoing experience is not, dead, though. It is artisinal. Check out you local community operated retro/indy/arthouse theatre, many have flourished in this post covid era.