I wrote this on Reddit recently:
"It's about control, which leads back up to money.
"Windows is the default OS and IE the default browser. This is also why IE is broken. Microsoft doesn't want IE to render the same as its contemporaries because then you don't need to test on IE anymore, which means you don't need Windows anymore.
"Microsoft controls things this way and it's been part of their corporate philosophy for a long time -- Embrace, Extend, Extinguish. They make something mostly compatible with the standard or competing product and then add proprietary extensions or quirks, and their marketshare alone forces people to take notice, and the hope is that eventually people will forget about the non-IE stuff and not bother to test on it anymore, meaning that now things don't work unless you have IE, meaning that you can't use the internet without Windows. That doesn't happen as often with the internet anymore, but as most of us know, it was quite successful for a pretty long time, and it's still successful for many non-web technologies (see DirectX v. OpenGL, etc.).
"And while things are no longer panning out to complete MS dominance, IE still plays a major role in defining what techs get on the web and what doesn't. For instance, crappy HTML 5 support because HTML 5 harms Silverlight. This is all intentional, don't fool yourself."
Not sure what you mean by "Microsoftie", but it'd be interesting to hear an MS advocate's or employee's position on this.