Although I think you’re correct if you stipulate Windows NT and XP, this is not true for Windows (historically) in general. See, MS-DOS was specifically a single-user, single-computer OS, whereas UNIX derivatives are inherently multi-user. I think this fact alone (especially when combined with backwards compatibilty) is responsible for many Windows policies and problems, such as the “default Administrator rights” issue.
That’s not to say these things aren’t being solved; just that not being designed for networked usage, earlier incarnations of Windows actually were easier to crack into.