> I can't see how you're accounting for the cost/value of the use of the property

That's what the rent/buy calculators are doing! It's summing up all the cash flows for owning a property (down payment, mortgage, taxes, maintenance, etc, and then crucially selling it after 30 or so years) and for renting a property (rent, and investment income from money that would have otherwise went to down payment/mortgage), and telling you how the results differ.

All I'm doing is tweaking 2 of the parameters of these calculators: The rate the home appreciates in value, and the rate cash investments appreciate in value. Everything else stays the same.