Some time ago there was Zeronet (abandoned) that worked like this. The problem was that the speed of the site depends on how many users share the data and for heavy things like videos it was a catastrophe. On zeronet there was even a social network similar to facebook/twitter called ZeroMe: https://zeronet.io/docs/it/img/zerome.png

It was a really cool project, it’s a shame it’s not being developed anymore.