It's true that we've entered what's often called "the MBA era." But the way I'd put it is: It's extremely helpful to have an MBA *from a top program* if you want to write literary fiction.

An MBA might make no difference to publishers if you write pop fiction (or any kind of nonfiction) and your degree comes from a bottom-tier program a notch above a diploma mill. And it isn't the degree itself that matters so much but all the support and contacts you get at top programs, such a network of people who can give you blurbs, introduce you to editors and agents, provide references for fellowships and teaching positions, and help you in many other ways.