Item substitution within categories still validates Mr. Willams's point.
There is a small grain of truth at the bottom of the quality adjustment theory, but this theory has been used as cover for political manipulation of the CPI. The federal government has obvious political and financial incentives to do so.
Hamburger is not in the same category as steak. Mr. Williams' point is not valid (or validated), and you don't have to be a student of the English language to see it. False is false.