I agree - an MBA is not engineering, and many in my class would have been unable at that stage to finishing 3rd year engineering mathematics. A few of us had engineering backgrounds though, and some very deep at that.
However there is (usually) a deliberate effort to overload students with volumes of work, so that they can figure out how the real world works and work in teams.
Also in my MBA course students had a minimum of quantitative work they had to do, and if they wanted they could dive deeply into the more serious mathematics in certain courses. It was part of the expectations that people who were more technical or more experienced in one area would help out those who had less experience, and vice versa.
Engineering mathematics is not for everyone, and indeed not required for every MBA graduate, but it certainly helps for the more quantitative courses. And finance at one school can differ wildly from finance at other schools. Look for the professors. Look at the courses people take.
But also look at the culture. Some universities are focussed on the money, others, like Yale, on much wider impact in business and public service.