The problem with a "barracks" to "store" a unit is that it allows a realm to prepare a massive double-hit during war time. A realm could all recruit to max, store the units on their estate, then recruit another for an attack. After the attack they just pick up the stored unit and hit again. You get a massive double punch, a huge advantage over any realm that did not have one of their own ready.
Wasn't something like this possible many, many years ago with militia? Maybe someone who played 7-8 years ago can remember better...
I'm pretty sure that you can still do this, with the General assigning militia. It may cost an hour per militia assignment, however. not sure. Also not sure if they did away with this.
(you know...I have two generals...I'll check the next time I find some militia)
