I was there when it all began! Michigan started the ball rolling by taking management accounting from being a 13 week course in the MBA program to a seven week course! Over time this lead to more and more programs at the MBA level reducing the number of contact hours in MA.
Without MA in the core of the MBA program at a full course level, quickly management control systems courses begin to die out, and soon the only accounting elective left was financial statement analysis and maybe some hybrid intermediate accounting course.
Who picked up this missing accounting? Marketing, Human Resources, strategy, and finance all have tried to do so! But try to get an MBA to do a break even analysis or a budget! These were considered obvious skills a generation ago and with the entrepreneurial and gig economics of today one would think they would be core skills in any MBA!
As for designing control systems, incentive compensation plans, and other key tools of modern management, at the MBA level accountants are notable by their absence. But these are all areas that we excel in with great research that has practical importance.
Look what we did to ourselves! We only have ourselves to blame.