> renting to be more expensive than a comparable mortgage.

that doesn't sound plausible. May be for a select few properties that are in some unique circumstance (e.g., the seller of the property would sell underpriced because they needed quick sale).

And often, in arguments like these, the rent is the rent, but the mortgage is purely the interest on the loan, and doesn't count the maintenance cost, and doesn't count the deposit required (which has a cost, ala the cost of capital). If you added up all these costs, it exceeds rent.