I haven't used torrent in a long time. Does it have any other usecase than piracy?
Linux isos are frequently pointed out as a use-case. I've seen it used for distributing neural network weights recently (stable diffusion and others). Rainbow tables and password lists too: https://freerainbowtables.com/
I have used it to efficiently distribute big files (disk images) over hundreds of computers in LANs. Computers on local switches can exchange data with each other, and computers can come and go on the network.
For instance, if you're in the infrastructure group in a company, and you need to distribute VM images around the place, it's great.