A large class of soft metallic ferromagnets like Fe-Ni-Al and Ni-Zn ferrites exhibit hysteresis behavior which is independent of the frequency of the applied magnetic field. We show that the reason for this is that the microscopic relaxation time is inversely proportional to the frequency of the applied field (for low frequencies). The argument, based on a scaling invariance of the dynamical equations, breaks down when thermal fluctuations are included.