Originally Posted by Russ Roth

With a rim brake it isn't only a few, looking at a front wheel, the torque of the hub will transfer that torque through its momentum to all the pulling spokes at once, unless you're arguing that the rim is deformed while riding bit then we would have to look at how that deformation changes as braking changes the dynamics of the system also recognizing that a disc wheel is under similar deformation. The trailing spokes are of course slightly unloadeunloaded.
But with a disc brake, using a cheap underbuilt one which is easy to grab off ebay, the initial force, even though it is truly only momentarily, the force is directed through the braking side pulling spokes only while the trailing spokes will be weakened. Either way, discs stopping the force in a shorter time span results in a greater transfer through the spokes and into the rim.