You’re kind of describing BitTorrent! And it works brilliantly. But it’s still challenging with such huge data archives to get many seeders… who has 390TB spare.

But I think I get what you’re saying, where it’d be nice if you could just say to the internet at large “here’s 5TB of storage to play with on a reasonable internet connection” and the entire universe of torrents would magically figure out what blocks of data to put on your drive to ensure enough duplication for all torrents, regardless of their size.