I think it's been a while since that rule was stated in the thread, so She/He/They/whatever probably missed it.

[@KoL] Everyone has to be a private or PFC, just to keep some semblance of order. Otherwise we'd be running around with a squad of corporals and lance corporals, with everyone overruling everyone else's orders. Zark's character is the one exception, having been promoted when we found out we needed a 2IC to keep things running smoothly.