They can. Think of it like a torrent file and a webseed. You can freely use torrents to distribute your content, but if everyone who has ever downloaded it goes

They can. Think of it like a torrent file and a webseed. You can freely use torrents to distribute your content, but if everyone who has ever downloaded it goes offline, any new downloaders will be stuck at 0% forever. The only add on here is that you can pay some service in filecoin to keep seeding your torrent forever.