Transferring the torrent metadata is pretty trivial and can be done via a wide range of methods, and having that flexibility can be nice.
Unlike HTTP, you get reasonable retry behavior on network hiccups. Also, more robust data integrity guarantees, though a manual hash test is probably a good idea either way.
At least among people I'm throwing TBs of data around with, torrent infra is common and it's nice to not have to deal with some special-purpose tool that, in practice, is probably a pain in the ass to get compatible versions deployed across a range of OSes. Basically every platform known to man can run a torrent client of some sort.
And obviously, no dependency on an intermediary. This is good if you're trying to avoid Google et al. That does, however, bring a potential con: if my side is fast and your side is slow, I'm seeing until you're done. If I'm uploading something to gdrive or whatever, I can disconnect one r the upload is done. If you control an intermediary like a seedbox, that's less of a problem.
In general, though, torrents are pretty great for this sort of thing. Just encrypt your stuff beforehand.