Wouldn't it be kind of zero-sum? Either you live in the house yourself, than the calculations apply, or you live somewhere else, but then (simplified) your rent equals the rent your renters pay, so it cancels out and the calculations would still be correct.
I'm sure other landlords make a very good profit month to month also. But if landlords were making a loss in real terms over years, they would probably stop doing it.
This is one of the principal arguments that the local housing market is overinflated. You can't take out a mortgage to pay rent, so it tends to be better reflect economic fundamentals.
Don't assume everyone has a new mortgage at full market prices!
That said, I don't see that as being the most important metric. Today, in Seattle, it's cheaper to rent than to buy. It might be cheaper to buy ten years ago than to rent today, but that doesn't have much bearing on a rent/buy decision tomorrow.
I grant you that if you own long enough, your costs will someday be lower than renting the same space. But that's a tricky calculation, and your break-even point depends heavily on your assumptions for inflation, rent increases, interest rates, etc. And over the five-year timespan that most Americans own a particular home (very few people spend 30 years in the same house anymore), it's not even worth considering -- you'll lose far more money to interest payments in the first five years or a mortgage than you'll gain in savings over rent.
My point is that we can both be right. Eventually you'll break even on monthly costs, even if you buy at today's bloated prices. The question is, how long is "eventually"?