Not at all what the GP said.
They aren't saying landlords are the problem, they are saying Institutional Investors and Foreign Corporations being landlords are the problem.
Wait, you're not answering his question. "Institutional investors" rent out houses at a scale individual owners can't, and have more resources to maintain those properties and respond to renter complaints. Why isn't a carefully-regulated market of institutional single-family-home lenders a good thing?
There is absolutely nothing wrong with institutional investors buying tract homes and renting them out. Nothing! It brings the benefits of living in such homes to people who otherwise would be excluded from them by the financial credit system.