Well, the Internet everyone uses isn't really designed for it. HTTP is a request/response model. But the model of filesharing is that I have a bunch of data and I want to send it to you, not that I have a bunch of data and I want you to ask me for it.
File sharing over the internet means setting up a webserver, after which it works beautifully. But nobody wants to do that. They want to use browsers.
TCP isn't asymmetric in the same way, but who's out there thinking of raw TCP as "the Internet"?
It's a shame Torrenting gets such a bad rap. If I want to share a large file with somebody who knows what they are doing, I encrypt it, create a torrent, send them the magnet URL and then they can download it and decrypt it. No web server needed.
Unfortunately, a lot of the time, people have no idea what you are on about, or even if they do, they are behind a corporate firewall with torrenting blocked/on a work machine and can't install a client.
File sharing over the internet means setting up a webserver, after which it works beautifully. But nobody wants to do that. They want to use browsers.
TCP isn't asymmetric in the same way, but who's out there thinking of raw TCP as "the Internet"?