No, it is not a crutch, and there is no rule about having to have the spindle under the ball of your foot with flats. Or that you have to place the spindle in the same position with flats and clipless in general. I know that for me, I tend to place my foot on flat pedals with the spindle farther back than on my clipless. Nice thing about flats is that you can put your foot wherever you want for whatever situation you are in.
There are some folks (particularly
this guy) advocating for running the spindle farther back on the foot with flats in general.