[thejosh]

Could also be that some people only used Macs or Linux or Unix or iPads.

[dsr_]

I hope that's a joke. In case it isn't: IBM PC predates all of those except UNIX (and you wouldn't think much of the pre-1980 UNIXen); CP/M, which originated the standard, comes from 1973.

[trimbo]

Sure, but the Mac came out in 1984. And don't forget the Apple II and C64.