MB expanded to a similar number of questions as B5 would remain useful – for the workplace. B5 including empathy-systematizing would explain the difference in facets (subtraits) which vary by sex. So no it’s not bullshit. it teaches normal folk to think about motivations.
I worked on this question, and the delta between Big Five and MB is trivial. And it’s due to the low number of MB questions(stability of results) & B5 includes neuroticism vs MB includes empathy-systematizing. MB is about all the normal folks can use in a business setting. So No.