It's a defense mechanism for sure - but not for that reason. The real reason, in my view, is that techies are terrible at recognizing intelligence/skill if it does not somehow relate to math, logic, or, more concretely, code. I have no idea why, but the shoe fits.
When presented with the numerous and obvious counter-examples to "MBA's are full of shit", they clam up and resort to "yeah, but they're assholes, immoral, and basically stole their way to the top".
If you can't code, you're not smart. And if you're not smart, how are you more successful than me? (Success is derived from smarts, right? Dammit, I'm SMART.) Therefore you must be a cheating douche bag. And man, there are a lot of you cheating douche bags.
No, the problem is not the MBA. It is the refusal of some to accept a broader world view in which different people can do great things despite vastly varying approaches and skills.