Sci-Hub is not "A website" though. It's a archive, archive of scientific papers that can be served by a static file server, IPFS or torrents. Have the DOI be the filename of the paper, and now you even have a DOI-lookup functionality in your static file server.
Sure, you could do that over IPFS. But if you really want scale, censorship-resistance and wide-spread usage/storing of it, you'll use torrents (today, maybe future will be different)
IPFS is built on torrent technology so it has those same proprieties. The advantage here is that IPFS additionally handles the front-end - the website, search and any future features that might be added like a blog or forum.
IPFS is not "built on torrent technology", it does borrow some of the ideas that Bittorrent also uses. And no, IPFS won't automatically give you search and other things, you have to build those yourself, same as if you used Bittorrent.
Sure, you could do that over IPFS. But if you really want scale, censorship-resistance and wide-spread usage/storing of it, you'll use torrents (today, maybe future will be different)