I am sure Erina will be eager to help fix the sexless part.
There is a fair share of old software that was never updated to run properly even on win7 involved in banking, accounting, airport control and other areas, because existing option works great, the company who made it is dead, and no one else offers an option that "just works". I've also seen a dinosaur running win95 with some homemade soft in university because "we used this program for as long as I remember and I don't want to learn anything new". Another possible option is they have some old printer/other hardware with drivers that just refuse to work on anything newer, but on the metal side it's an awesome machine so they just take an L. Star Force, that used to be a go-to DRM notoriously breaks any version of windows newer than XP (regardless of their official site telling you it's totally cool) but I don't think if it was ever used for work software and not just games
Or they are fucking cheapskates who don't want to pay for new windows, which is probably the real answer