I'm sympathetic to the goal of achieving affordable housing, but by this logic why would we let private companies run anything? We do because private companies

I'm sympathetic to the goal of achieving affordable housing, but by this logic why would we let private companies run anything? We do because private companies are often good at running things and usually their profit is small compared to the benefits they bring by being competent and professional. This is far from always the case, of course, but in my experience the renting market works well and I'm happy I don't have to deal with the hassle of owning an maintaining part of a building.