Miles I yield to your experience, as surely it is greater than mine, however your evidence is anecdotal, not scientific.
I have to agree with the others who have mentioned what you have not - you are diluting the ammonia in the bag with "fresh" tank water. Particularly if you have put an ammonia neutralizer in the bag such as amquel, or Prime, there should really be no downside to subsequent drip acclimation. You raise some excellent points on water chemistry but the addition of water conditioner negates all the concerns you have raised. So really what is the harm in a drip acclimation, so long as the appropriate measures are taken to detoxify the ammonia?
I'm chiming in because I'm in the situation where I'm moving my fish (large fish) a long way, but I'm also moving them from soft water to hard water. A PH swing of under 7 to over 8, and a GH of almost nothing to near the top of the chart is just not something I want to risk "netting and dumping" with. However raising the pH and affecting the NH4+ in the water after a long car ride is also a bad thing to be sure. My plan currently is to dose the transport water with Prime and test it for ammonia, re-dosing as necessary, then drip acclimate, and THEN move the fish to their new hardwater tank.
I suppose one major question left to answer would be - how well do water conditioners work? Do they actually remove the ammonia they say they should? How fast? I've noticed before that when I use prime to condition water going back into my tank (a cycling tank, so there's ammonia present) That the tank water still has ammonia in it after a water change and dosing with prime, so what gives? Is it all just advertising?