For many with unstable ISP connections, http downloads can get corrupted. Torrents are superior in this regard as the file gets split into blocks that each get checksummed for integrity after completion. This helps to ensure that the large iso is actually complete and won’t just be garbage on an attempted install. Even if you checksum the iso from http download, you have to pull the entire thing again if it is damaged whereas the torrent would just repull the damaged blocks automatically.