They're traditionally heavily interdependent on each other and almost mutually inclusive. Traditionally if you use Enterprise, you must use Exchange, you must

They're traditionally heavily interdependent on each other and almost mutually inclusive. Traditionally if you use Enterprise, you must use Exchange, you must use Office, you must use Windows, etc. You could fudge it and try to use other tools, but it was generally a complete PITA. It's getting better than that (Azure for example & node.js), but the change has come in the last 3 years or so and as someone else noted in thread, that they could open source so much stuff so rapidly shows there was a lot of departments chomping at the bit to start decoupling themselves and moving forward.