"the system seems to screw over people who do amphibious things"
I have to agree with WEBF (not my default setting ) - certainly seems to be the case in the RN. Probably because they are called upon to do it so rarely - how many times since '45 for example? Read the runup to San Carlos and it's clear they were very short of hands on experience - a few specialists, mainly relatively low rank, trying to beat some sense into the upper echelons as to what could and could not be done across a beach.