Bart, you may well be absolutely correct in everything that you've said, but since I have quite a comfort factor in reloading the way I do, I'll keep doing it. But...what I can do is a 'reverse' test, and I think I'll try that. I have one very accurate rifle (220 Swift) that was set up for me by a top level gunsmith years ago. I think that I have some unprimed Winchester cases that haven't been weight sorted nor prepped in any way. I'll load them up with my favorite and best pet load and see how accuracy compares with my highly prepped and weighed cases of the same make. I'll come back with the answer. Probably take me 10 days to 2 weeks to get the data.
One thing that I do know about that rifle is that it shot its best with Norma cases. When I switched to Winchester, groups opened up just a bit. For a time I had plenty of ammo loaded in both case makes and could shoot both for comparison. I hoarded the Norma loads and used them for shots that really mattered. There was a difference, though it was small.
I'm almost finished with my shop being in "woodworker mode" and will soon be back in the ammo biz.