You are talking about an artificial situation that has nothing to do with the way people use computers.
Google now has a policy of not letting people use Windows machines because that is how their network was hacked, through Windows machines. All the programmers were already on Mac on Linux. So this affects the non-technical people at Google. That is a real-world situation.
If you are looking for a secure computer, I have one for you. It's an old Dell laptop running Windows 95. It's secure because it's in my storage room, it's not hooked up to a network, and you will have to get the key to the room from me. At last, we have found a secure Windows machine.
So tell me how the past 3 years where OSX was hacked easiest and quickest can’t be applied to real world scenarios.
I can see it happen very easily in the real world. Typically just requires a user to navigate to a website.