Arm bands are not new nor exclusive to the 3rd reich.
watch Dirty Dozen :)
Armbands or other readily apparent identification are always being used in quick tactical environments, especially in MOUT operations. Desert Storm 1990s, every vehicle had orange tarp. Not very camouflaged IMHO. Ukraine street assaults show different colored armbands everyday in certain units.
Arm bands were required by all neighborhood air raid wardens throughout the U.S.