No it isn't? Grail knights are busy being awesome, so aren't sticking about with a slow army lugging warmachines behind it. Esp the KoE ones which are immobile in game, meaning they'd be disassembled to transport to battle.
Realms are tied in due to feudal law and Aspirants just want to prove themselves so it makes sense that they'd stay. What about pegasus knights, who in my head are more vain than Grail Knights? Why do they stay?
Look, I'm not saying these issues can't be sorted out, but the project doesn't have a history of quickly sorting out fluff issues but very very quickly solves most balance issues.
Never argue with Idiots. They drag you down to their level and then beat you with experience.