[gnoupi]

In theory (assuming that there are links to everyone, and no way to have separate networks) (it's of course a theory only, but seems very likely that there are "massive users", who have files of "every kind", connecting the different groups), as long as you both connect to one who is connected, it will work.

Although this is quite the extreme case, and not really the purpose for Bittorrent to begin with, I guess. The main interest is load balancing of popular downloads, not finding the one person with the one file for you.

[cookiecaper]

I've actually found torrents to be a great way to share large files with a friend. There's no invasive upload dialog or locking, no practical filesize limitations other than the free space on my friend's computer, you don't have to upload to a public-facing server before your associate can start downloading, port forwarding is handled transparently by UPnP, client software is user-friendly, easily available, and often already running anyway, and it's easy to scale if another friend wants a copy at some point in the future.

Of course, TPB switching to magnets doesn't really affect this. Torrent files are still used to provide information on the download, they're just distributed from within the P2P network instead of TPB itself. If you have a torrent file to share with an individual or small group instead of the whole world, there's no reason to stop using torrent files directly.