Soft or hard, I've used a steel on 4-star blades since about 1980. Mostly with a ridged steel but now with ceramic and a smooth packing steel. Both of the latter are better than ridged steel. Don't know what "necessary" is intended to mean but a steel is one way used for generations to touch up a blade. They all can't have been wrong for so long can they?
3/2/15 at 4:56pm