"Providing rental houses" isn't bad. "Buying up all the houses currently for sale, so that your only option is renting, and that at a rate we control" is bad.

"Providing rental houses" isn't bad. "Buying up all the houses currently for sale, so that your only option is renting, and that at a rate we control" is bad. ("All" is an exaggeration, of course. But they have enough capital that they can significantly reduce the available market in several metro areas. The claim is that they do exactly that.)