This is about instructing vs the real world.
A student is taught to retract flaps first, then as he adds power, he has a stable 'wing' to climb out on. Conversely, having a student add power first, could put him flying in ground effect pretty fast, then retracting flaps without adjusting decking angle, he could stall, hit the ground, etc.
In the real world, landing a jet, fuel truck pulls out on the runway...you add power first, to get the plane accelerating/flying, get up into ground effect ASAP and retract flaps to TO position, and get over the obstacle.
So this is about have the ability to adjust as the flaps are moving...a student can't, a pro can.
Without power the plane isn't going anywhere, and this question is quickly answered when you have an obstacle up ahead, and your decelerating rather then accelerating.