I love that throughout this entire argument one massive factor has been barely mentioned, armour is designed to divert energy either through dissipation such as we see in lamellar, padding, scale and mail or through deflection which is more common in "plated" armours. Now I'm sure that you've all seen the curved nature of the helms and shoulder armours in game this is in effect to prevent a direct energy transference if an axe, mace or sword strikes the armour it is incredibly hard for the attacker to hit at an angle that transfers energy directly to the target which would produce heavy concussive effects, "blunt" weapons usually have flanges or points to help reduce the impact area this is to one increase force and two to reduce the chance of slippage occurring which would make the strike ineffective. Against a well designed helm a thrown rock is quite likely to be deflected off of the target especially from the front as the target need only lean left or right to avoid the shot (impossible in game) meaning a lot of the calculated impact would be lost.
Realism can't be argued in a game sadly as simple tricks that someone trained in armour can use to reduce the impact of an attack or completely negate it can't be adequately introduced, simply put heavily armoured troops would be highly resistant to many forms of attack due to their armour and skill in use of said armour this can be represented by significant damage reduction especially against low danger attacks such as thrown rocks from looters. Throwing weapons are effective however launched weapons are more so, throwing rocks as armour got better became more of a siege defence tactic as the angle of attack is a lot more effective plus gravity is damn scary when dropping weight on people.
Also blunt weapons should have a chance of being lethal, a mace to an unprotected head will make a mess not knock someone out
Final note: I'm not saying immunity to thrown rocks but realistically rocks hitting an armoured individual trained to use their armour is so low in danger that we should be taking at max about 7-8 damage and that's if it strikes well at speed and the target isn't aware. Dropped rocks however should do stupid damage.