All banks are is the middle man between someone with money and someone without money. And they charge to help make that connection.
All rental owners are is the middle man between someone with a home and someone without a home. And they charge to make that connection.
Granted, I'm not a big fan of owning rentals. I think as an investment it is more risky than most realize or understand. No one takes out debt like they do for a rental and are so excited about the prospects of it. The good news recently is its turned out quite well for people. Debt is an amplifier.