If this guy has a problem managing his "business" then he should be in another business. FWIW, people who have the most success with rental property are those who have hands on skills and can fix problems themselves.
I rented twice from a guy that owned 16 houses in southern NH.
He went to plumbing and heating school so he could work on them himself. He also kept his rents a little under the market. He said that way people tended to stay in his apartments longer. When apartments turn over you have to paint and replace carpets. If people stay in them, you don't have to do that. He also plowed the snow in the winter. He would discount rent for one tenant in each house if they mowed the lawn and kept an eye on the property. Even though he lived in town.
He eventually passed and his daughter and son in law now manage the business. Last I knew they had about 60 apartments all in one town. The BIG thing the author of the article leaves out is ASSET DEPRECIATION. Running a property rental business allows you to depreciate company assets. That asset is not onlt the houses, but the pickup truck, the lawn mower and any other thing purchased to maintain those properties. This is why a COMPANY can afford to buy a $100K pick up truck every few years. There have been years recently when the Federal Government allowed you to depreciate the cost of that asset(the pick up truck) in ONE year.