Seems like you completely ignored this part: "compared to some major asset classes that are omitted from consumer inflation calculations"

sp500 going from 2500 to 4000 in the same year is 60%. Yes, a 20% price hike compared to a 60% price hike makes for a cheaper outcome in the end, when gas is "compared to some major asset classes", in my example the US stocks. Why is this so difficult?

I ignored it because it is irrelevant. People's purchasing power isn't based on the stock market index, it is based on their income. Even a retiree who is net withdrawing... a 60% upwards move in the stock market doesn't mean that retiree has 60% more purchasing power this year.

Use some of your purchasing power on an economics book.