This is mostly just an appearance thing unless people are clipping the coins, in which case vendors would probably either reject them or turn you in to local lawmen who had punishments for doing things like this like death (lol).  The US government also used to offer a service to turn your bullion into govt coins for free I think.  It's overall not a big deal since the things are still recognizable a thousand years later.  They don't actually require overhead to "exist".