Yes, but not by "growing the pie"; MBAs increase profits in the sense that they reduce the share of profits going to workers (at least according to this paper; I'm not familiar with the rest of the literature on this subject).

From the abstract of the paper: "...Exploiting exogenous export demand shocks, we show that non-business managers share profits with their workers, whereas business managers do not. But consistent with our first set of results, these business managers show no greater ability to increase sales or profits in response to exporting opportunities..."

I would say a system which continues to exist, despite predictions it should fail, is more effective than the model which predicts it failing. You and I may think that growing the pie is better than turning the screws, but the system doesn't care. It just does what it does.

Maybe I'm wrong here, but I'm reading many of the comments as: "The goal should be X, managers do Y, so managers should stop" when the goal is not X.

yes on planet manager they do quite well. they get paid a lot more and they laugh a lot.