I can remember when the old head troops bitched abut the ‘new’ nylon button replacing the ‘tried and true’ metal buttons.
BTW - it ain't a Zipper son - it is a fastener, interlocking slide, metal. Zipper is a Brand Name you know, like Trojans or Marlboro.
They tried to get rid of anything metal on the body due to mines. When I was in they were phasing out the metal web belt buckle with nylon.