Very common on Slashdot fifteen or twenty years ago. The Pirate Bay trial was a big story back then, for instance, and there was advocacy from the copyright cartels to ban the bittorrent protocol. Another hot story was when Comcast dropped customers for using too much data despite being on “unlimited” plans, justified because only a pirate would download so much. Hence, “You can’t do that, I use bittorrent to download my Linux ISOs!”

It really was common in the early 2000s for Linux distros to provide torrent downloads. Internet speeds were such that downloading peer‐to‐peer could be significantly faster, and (probably more importantly) it saved the distro mirrors a lot of bandwidth. I think this practice has mostly died out among newer distros, but distros from the era such as Ubuntu or Arch still provide them.