Ok. Where is this documented anywhere in game ? It lists it as a pre-requisite. This isn’t how other buildings work. If you lose your blacksmith you can’t build siege workshops. This does not look like intended behaviour. It is counter-Intuitive and also simplifies strategic options in game - taking out critical structures should matter in an RTS.
This is not correct. If you already had a blacksmith at one point you can build siege workshops, even if the blacksmith was destroyed in the meantime.
Same for the other military buildings. If you lose all of your barracks you are still able to build archery ranges etc
I guess this depends on how you think about it. To my understanding it works like this: The pre-requisites must be met to unlock the corresponding part of the tech-tree. They are no pre-requisites to build the building. In other words: Parts of the tech-tree are unlocked as soon as their prerequisites are met. It doesn’t matter if the corresponding buildings are destroyed later on.
Build mill → part of the tech-tree to build farms and markets is unlocked (however, markets are only accessible from feudal age onwards)
Destroy mill → you can still build farms and market (however, markets are only accessible from feudal age onwards)
Build blacksmith → part of the tech-tree to build siege workshops is unlocked
Destroy blacksmith → you can still build siege workshops
You are in Dark Age
Build mill and lumber camp → part of the tech-tree to advance to feudal age is unlocked
Destroy mill and/or lumber camp → you can still advance to feudal age
You are in Dark Age
Build mill → you cannot yet advance to feudal age, since 1 dark age building is missing
Build lumber camp → you cannot yet advance to feudal age, since at this very moment you only have 1 dark age building
Build mill → now you have 2 dark age building at the same moment and the part of the tech-tree to advance to feudal age is unlocked
Destroy mill and/or lumber camp → you can still advance to feudal age, since this part of the tech-tree was already unlocked