my experience of "windows only" admins is that in general they're not actually terribly good.
**sigh**
As a Windows admin since NT3.51 I suppose I should take offense at that, except that you said "in general". Windows systems **CAN** be made secure, and for no cost and not much more training, but since politicians refuse to fund IT departments adequately the type of people they end up hiring tend to be close to the bottom of the barrel. I've encountered the same situation at police departments, public works, and our state data center. I've seen same thing happening wherever corporate executives prioritize their bonuses and stock price over security, such as healthcare (abysmal), financial industry (awful), energy (bad) and pharma (not good).
I spent the last 16 years of my working career in physical security (key cards, cameras, alarms, etc.), and for the first half almost everywhere I was given god-like access whenever I requested it. Then I went to work at Amazon Web Services and ran into a brick wall. The Windows admins (almost all security systems run under Windows) were exceedingly tight-assed and would not allow exceptions to their security policies (of course we didn't allow them exceptions either, so I suppose that was fair). The result is that AFAIK to this day there has never been an external hack of AWS, either through Windows or Linux/Unix, the only data leaks have been from contractors with data that they were not supposed to copy out of the system (mostly test data).
Bill Gates' moment of brilliance was when he realized that "good enough" was actually good enough for most customers. Unfortunately that also enables people who are "barely good enough" to become admins.