Yes, I'm sure internal politics had something do with it. Sinofsky wasn't the easiest guy to work with. You know whom else I've met in the technology business who wasn’t that easy to work with? Guys like Bill Gates, Steve Jobs, and Larry Ellison. While being self-centered and cocksure of yourself causes friction, when you make successful technology and business decisions, it doesn’t kill your career.
Nice guys usually finish last at top tech companies. What counts, what always really counts in tech, is delivering the hot technology on which people spend serious money. If you blow that, and you're not the CEO, you're history. Just ask Scott Forstall, former head of Apple's iOS.
No one inside of Microsoft is saying that Windows 8 is a blunder. That is, they aren’t saying it yet. Give it a few years. But, ignore all the rah-rah Windows 8 fan-talk and take a closer look. What do you see?
I talk to a lot of developers, and they agree. Windows 8 mobile was never attractive to iOS and Android programmers because there wasn't enough money in its market. Windows developers, those with years of experience in .NET, found WinRT to be a pain to program in. Such fundamental questions as how Windows Phone 8 APIs will merge with Windows Store (a.k.a. Metro) app APIs remain unanswered.
Frankly, I'm surprised if anyone would buy a Surface RT. Whether you compare it to an iPad, an Ultrabook, or a Chromebook, Surface RT is over-priced and under-powered. It's a toy for early adopters and true Windows RT developers (https://www.zdnet.com/i-love-windows-8-but-surface-rt-is-for-early-adopters-and-developers-7000006459/), not ordinary users.
Windows 8 PC sales also don't look good. The analysts describe Windows 8's outlook as "mixed." Personally, I've been talking to both OEMs and retailers. They are, in a phrase, not happy. In particular, they're getting push-back from users who want "real Windows," not Windows 8.
Here's what I think really happened. The straw that broke the camel's back was that neither Windows 8 nor Surface were blockbuster successes. Had they been so, none of the rest would matter. As it is, Sinofsky was fired for Microsoft's sins.