But if you do that for as long as your mortgage lasts, at the end you have a house worth $500k, probably way more, you haven't paid a single dollar of your own money towards that mortgage and still got $18k of profit per year.

To put that money in a savings account you would need to have liquid $500k to begin with. With a mortgage, you borrow money and then rely on somebody else to pay it back

Of course that tips ever more in your favor the more money you have to begin with. While I think anyone being landlord is unethical, by far the biggest problem are real estate investors that buy 100s or 1000s of homes