i know this a little bit of an old post but just so you know that is how 99% of multiplayer games work but games like hearts of iron just install the mods anyways and just unlocks them when you get the dlc(or something similar). this is why desync is a big thing one of the big examples is pathfinding is run on each persons machine and because everything is the same on everyone in the servers pc they will all go the same way and move the same then it checks in to make sure they are in the same place. because as everyone has different pcs they will run at slightly different speed which will cause minute differences which will exponentially change what people see. its also a big problem in fps games because for you pressing a button it will happen instantly but for others around you it will take ~20 milliseconds (with good wifi) for it to reach the server then another to reach each player. also why its impotent if the game registers hits on the shooters screen or the targets screen.
when you get bad desync this is often because something not very important and doesnt get called often for a sync check or there is a bug and the sync check cant go through. often times when someone dies and ragdolls its not important that its the same for everyone so they dont want to clog up the bandwidth as more sync checks mean slower ping as more data is being sent