alt Hacker NewsCastle building was in fact a function of the downfall of the carolingian empire that until then kept it under control and only granted the right at strategic locations. Most castles simply made a local lord unfireable by his king since besieging a castle was way too expensive for a regular dispute. The castle building shifted the power to the local realm, starting the feudal period for good.
Castles are thus more like domains where once you take hold of it, even the big powers have a hard time taking it away from you again
Seems more like the rule is:
> Building a castle is a very good idea if you seek to entrench yourself in the power structure of the kingdom. To do this, you must be able credibly mount a defence of the castle to discourage forcible eviction without major mutual destruction (cough too big to fail).
> Don't build a wooden cottage and expect it function like a castle with a garrison under your command. Even if you slowly expand it to a stone mansion, if you don't maintain a garrison, it won't work as a castle.
Sadly, building an game on someone else's platform is more like setting up a cottage on the land. You might be able to get some farming done and survive, but if the lord fancies the grain, you're out of luck. But also good luck finding land to farm without a lord. Peasant.