I don't think the media companies are capable of cooperating on a platform like that.

You mention Hulu which I think is a great example of that model failing. Hulu was originally a intended to be that kind of platform, and has at times included investment from ABC, NBC, FOX, and Time Warner. Now Disney owns a majority share in it and it's a brand under Disney's streaming services, and I think would like to just fold it into Disney+, but they'd need to make some sort of deal with Comcast for their minority share.