Why one company requiring knowledge of another's systems makes sense

A few days ago, one of my friends on Facebook shared the status of a page titled "WTF Facts". That status read

"You need to know how to use Windows in order to get a job with Apple."

At first this may seems like a rather unusual requirement for getting a job at Apple until one stops and thinks about it.  Apple offers the following programs for install directly into the Windows Operating system

• Quicktime
• Itunes
• Safari for Windows (although this may have been discontinued)
• iCloud control panel

Add to that, Apple's iWork Suite has inter compatibility  with Microsoft's Office files, allowing users to open up Word, Excel and Powerpoint files either in the desktop or iCloud versions of Pages, Numbers and Keynote

This actually goes the other way for Microsoft, as they have either programmed, or currently program for Apple systems these following apps

• Microsoft Office for Mac
• Microsoft Mouse and Keyboard Drivers
• Microsoft Windows Phone Software 
• Microsoft Silverlight (Slowly being phased out by companies switching to HTML 5)

As in the case of the Blog post that covers why Web Designers access so much hardware, good Developers in all fields need to be able to work with multiple platforms and technologies.