The potential user base for skyrim on macOS is much lower because there simply isn't a large user base of gamers on Mac platforms. Mac users of Steam represent 2.45% of the total user base in the following survey: https://store.steampowered.com/hwsurvey/Steam-Hardware-Softw...
I think it’s safe to say that Steam stats undercount the potential size of the Mac gaming market. There are a few reasons for this: - The trailing effect of Apple’s underpowered Intel Macs. For many years the average Mac was an Intel MacBook Air, which never had a hope of running many contemporary games. - As a result, few developers tried to target Macs, which meant Steam felt like a bit of a ghost town for Mac user…
Many users aren't going to go through the effort/expense of working around this.