Break the Matrix

I asked an ALF practitioner about the ALF/Crane treatment and he said that the alf appliance needs to make things wider before pulling the maxilla forward with the crane. He said pulling maxilla forward without making the arches wider will have it's own set of problems. I didn't ask what kind of problems he meant at the time but now i'm wondering what kind of problems he is referring to. What kind of problems can there be?

I wonder if its just the alf protocol? (with widening first with the standard alf and then doing braces or a diff appliance to for the crane) or if all face pulling methods need to be done in same fashion. Widen first and then pull forward? Can't it be done at the same time? You'd would assume so right? since plato's website says you should use the palatal expander with your helmet.