It's possible to attack this problem from multiple angles. As it stands right now the tenants that occupy my properties either don't want to own (grad students) or can't afford it (e.g., service workers, low-end "white collar" job holders in the bay area). By charging (significantly) lower than market rent, deferring or waiving rent, setting up very long term payment plans, and basically treating them like they're people with lives that shit happens to them in I do what I can as an individual. By working in other areas (e.g. with NGOs) I do what I can to contribute as an individual to a larger group effort to change the way housing works in this area.
Given that one person can't make the rental market go away, no matter how much they might want to, mitigating it is perfectly reasonable. I'd go further and suggest forming a Humane Landlord's Association with explicitly stated humane values.
