I agree to it. A sales or marketing manager will feel awful if he or she are asked to work as a financial controller or I-Banker. You must chose your career path base on your personality and interests. If you are very interested in sales or marketing jobs, a finance job may not be good for you because it need completely different qualities.
Sorry, Dajiqi, I did not read your last sentence carefully before since it's so small. I don't think it will be a disadvantage in application that you have worked in 2 different industries before. But if you have 6 or 7 years experience and want to change your career after MBA program, you must provide strong evidence to convince adcoms. That's not very easy. Take care.