I haven't seen much evidence to the contrary, either. All I see is anecdotes from both sides, so I'll give MBAs the benefit of the doubt. Speaking for myself, I am an entirely different person after completing my MBA. I've become an analytical thinker to a fault and maintain my soft skills. Learned a metric shit ton of corporate finance, business strategy and decent macroeconomics.
> Also, a lot of people have endured "elite" MBA's entering the workplace into positions of seniority with no prior experience and exactly the results you might expect under the circumstances.
Shitty people exist everywhere. You don't have the counterfactual to know if those bosses would be even worse without an MBA. Seems to me like that's more of an issue with HR hiring processes than with the intrinsic values of a rigorous MBA program.