World of Warcraft used a BitTorrent-like protocol for patches for awhile, as a default option if I remember right. https://www.bluetracker.gg/wow/topic/us-en/10043224047-need-... As an example mentioning it.

It became disliked because of various problems and complaints, but mainly disappeared because Blozzard got the bright idea of preloading the patchset, especially to new expansions, in the weeks before. You can send down a ten gig patch a month before release, and then patch that patch a week before release, and a final small patch on the day before release, and everything is preloaded.

The great Carboniferous explosion of CDNs inspired by Netflix and friends has also greatly simplified the market, too.