I do accounting for a lot of landlords. What he’s talking about is cash flow. Almost nobody ends up with taxable income from renting because the rent goes to the mortgage, property tax, insurance, maintenance, etc.
Before you crucify me on a barbed wire Popsicle stick, the part he’s leaving out is the equity he’s building at the tenant’s expense.
When he eventually sells the place, he’ll get hundreds of thousands of dollars that didn’t cost him anything. Whoever lived there just gets memories of that place they used to sleep in.