Ok Chop I'm going to try one more time.
Lets assume that you are hovering on your cold day, at sea level, at design max gross weight and it is only taking you 95% of your max TQ. Lets make this a hypothetical helicopter with a max gross of 2000kg. Your conning angle is, lets say 5 degrees and there is now 2000kg, less the weight of the rotor (lets make that 100kgs), hanging from that rotor i.e. the mast will have a pull of 1900kgs on it. The bearings that hold the mast in will have an upwards pull of 1900kgs on them. You now put 200kgs onto the back floor, right at the C of G, so no effect on C of G. To stay in the hover you have to add pitch, which increases the TQ and will increase the conning angle. Now there will be 2100kgs pulling on the mast and an upwards pull of 2100kgs on the gearbox bearings. There will be 200kgs more trying to tear the gearbox off the roof of the helicopter and there will be 200kgs more load on the frame of the helicopter that holds the floor on, all of this is 200kgs more than it was designed for. Lets say you take off and do a 2G turn, now you will have an extra 400kg load on all those components.
I think your confusion comes from the fact that you think the stress on the engine and rotational components is the same as the stress on the structural components and that is where you are wrong and as an engineer you should know this. You are correct that the engine and the gears in the gearbox won't be able to tell what the weight is and only feel the effects of TQ but as I have shown you above, this is not correct for the structural component's. Excess weight also has effects on other things like auto rotational performance but then you are a pilot and you knew that, right?
Still waiting to see your licences.