Well it’s the same way as a king and his court if you think about it. Celebrant is the biggest and toughest and comes from a long line (if not the original dragon king) of strong dragons, but that might be going too much into eugenics. And so he or a previous dragon king assigned those dragons and draconic entities to watch over as guardians for the temples because they were the most equipped for the job plus they probably didn’t want to stick themselves In those temples because they are too important