"the screw load up at the nut and not in the threads in the block."
It just does not work that way, the load applied is going to be distributed equally across the length of the bolt shaft from the under head down to the threads whether using bolts or studs.
Think of a bolt as a rubber band, as the bolt is tightened it stretches along its shank. The pulling of the shaft longer provides the tension to make the clamp load that keeps the cylinder head compressed.
In comparing bolts and studs, think of a rubber band being stretched and twisted at the same time, that is how clamp load is developed in a head bolt. Now think of a rubber band being stretched as it is held so the lengths of the band are held parallel to each other. That is how clamp load is developed in a head stud.
The single action of only pulling and not twisting is easier on the bolt shaft, and develops a more repeatable clamp load when torque is applied.
Remember the head gasket that you are trying to keep in place never sees the torque that is applied to the head bolts or studs. The head gasket sees the clamp load that is generated by the stretch of the head bolt or stud that occurs when sufficient torque is applied. The more repeatable the stretch, the more repeatable the clamp load.
