Apparently it affects any system that handles an internal calendar. MAME tries to get the date from your PC and then passes it to the emulated system BIOS. This is so you don't set the date every time you boot the system as if the PCB battery fails (just like your motherboard battery). You can see the date right there when you enter service mode (by default press F2 key).
NEOGEO in specific uses an internal clock to keep track of statistics operators can consult in service mode. Also there is at least one game (Art of Fighting 3) that makes use of the internal calendar for setting in-game events on certain dates (i.e. a character birthday).