His central point is that the "rent" you pay via the costs of homeownership are often approximately equal to the costs of actually paying rent. Since principal payments are on top of those costs, that is money you _can_ do something else with if you were renting, in this analysis.
Of course, that part of the analysis ignores the potential capital gain of the property value, which is often one of the appealing financial factors of homeownership. But the article also addresses that.
I can't speak to all markets, but in my experience in a HCOL city in the U.S., this is not true, at least anymore. Buying a place never broke even with renting an equivalently sized one, even in the long run. Yes, there are lifestyle advantages to homeownership, but at my current place and time, not financial advantages.
I live in a low-mid CoL city, so I guess this is all super YMMV, but even with a 5% down payment, a decent home would run me around $1.5k/mo in mortgage payments (including interest, principal, PMI, and an escrow payment for taxes and insurance), whereas an equivalent rental would run well over $2k/mo, possibly closer to $2.5k/mo.
Sure, I can (and do) rent an apartment for less than a house, but that means rent increases whenever the owner feels like it - my rent has been steadily increasing to the tune of about 5%/yr, and this year it was all the way up to a 7% increase.
I was in a similar boat years ago. The company I rented from wanted to increase my rent 12% year over year. I told them I didn't make 12% more money, spent a lot of time pleading, and talked them down to merely 9%. Rents were all over the place, and there was little I could do about, except move to a new apartment every year.
His analysis is that roughly 75% of his ownership costs are equivalent to a rent. To be able to invest the other 25% of his cost of ownership into something else, he would have to be able to find an equivalent property that he could rent for 75% of his total cost of ownership (or accept a reduction in the size and/or quality of his home).
I don't know how realistic that is across many different areas, but it's certainly not possible in many locations.
Of course, that part of the analysis ignores the potential capital gain of the property value, which is often one of the appealing financial factors of homeownership. But the article also addresses that.