[styrophone]

Access to capital gives larger landlords preferential rates, terms, and prices compared to individual buyers.

Unless the rental unit is a standalone single family home (and sometimes even then), economies of scale in maintenance and upkeep result in those costs being cheaper to a landlord.

Downpayments required for loans with good terms have opportunity cost to the buyer. On average over the long term, it has been appropriate to assign that downpayment a discount rate which is a net negative against average market returns.

If realestate markets are stable or reasonably increasing, mortgages are safe. But renting reduces risk of being stuck in an upside down loan, and risk reduction has value.

Despite all of these factors, you're right that rent includes profit, so in many cases it's wiser to purchase. But it's not as globally true as the parent comment suggests. The best choice comes from a balanced assessment of a variety of factors.