Unless you are Nyurei, you did not respond to my questions. You already have plenty of friction in finding the right Base items. Having Tempering Scrolls work indefinitely with a rising cost makes it similar to Masterworking which means if you want a Max Temper, you can get it, but it might take a while to grind to get it. Hitting Max Tempers twice in the same turn would take time.
Considering how you answered the question on GAs that you “pick up GAIIIs along the way” you even passively acknowledge that they are pretty rare. Most players won’t have GAIIs in all slots let alone GAIIIs in any given Season so you would STILL have a Loot Hunt.
I am good with the RNG being in the drop. The point is Tempering pulls the rug out from under you and takes a lot of time to (basically Identify an Item) to see if it is even usable. That really isn’t fun thinking you have a Diamond only to realize it is really a Lump of Coal. It is more satisfying to dig through Lumps of Coal to find a Diamond.
Honestly, I have also argued against GAs as well since this is the wrong kind of deterministic quality. Put the RNG in the Affix roll and have Rarity determine the Minimum Affix floor.