I find the idea of overall expenses only doubling for a family moving from OK or MI to a place like Seattle somewhat silly. The vast majority of household budget's largest expense by far is housing. If they want to downgrade their standard of living from a 3-4 br 2000+sq feet house, then maybe it will only double. Otherwise it could easily triple or quadruple, as the original article discusses and evidence for is easily found. Salaries are not 3-4x larger in high CoL areas generally. The difference is pretty stark even starting from an area like Metro DC/Baltimore that isn't exactly known for being cheap, but nowhere near SF, Seattle, NYC or Boston levels.
Yes, the square footage of my apartment went way down. Pretty much everyone out here lives in less space, generally it's less a "standard of living" thing than a "that's the norm" thing, but obviously if you really need 2K sqft you're going to want to evaluate things separately.
I see you've gotten Stockholm Syndrome already :) But yes, it is definitely an individual-situation type of thing for sure. I'm merely responding to the blanket assertion that just because you ~double your salary in a ~2x CoL area you are always coming out ahead. As you say there are assumptions built into calculators that you personally have to decide how to value, and how you value things like a good commute, schools, and a backyard can change over time as well.
You move and now make $120k and your expenses double to $80k. You're saving $40k; twice as much. But in reality, not all of your expenses increase that much, and the other benefits (bonuses, matching, raises, interest, etc.) are % based, so the discrepancy increases quickly.