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I don't see anyone claiming they are a requirement - just that they are beneficial and convenient. They are an upgrade to the originals. The stockers work as intended and designed but they were also applied with the mindset that the heads are to remain on for the life of the motor as long as a repair is not required - not as an easy method for upgrading to aftermarket heads.
Also, you won't be re-using your stock bolts. The LS1/LS6 use torque-to-yield (TTY) head bolts that plastically deform (permanently stretch) when you torque the heads down so they are throw-away, one-time-use bolts. Good thing they're cheap. Check your service manual.
You are right, I forgot these GenIII engines have the stretching bolts for heads and the damper etc. I don't have a manual, but that's what the forums are for. I was actually going to get a set of Trickflow bolts from summit as they are reusable and less than half the price of ARP's.