Earlier quoted context omitted.
This delusion that if only we build houses, the homeless, mentally ill and drug addicted will magically disappear from the streets...is based on what exactly? What does "housing policy" mean in the context of streets lined with tent cities filled with drug addicts?
surely you are not arguing it won't go down at all, right? So the question really is, what amount of homelessness will disappear. It may be that it is not cost effective. That is a reasonable possibility, i suppose. I think tho, it is a difficult prediction to make, and so shouldn't be dismissed out of hand.
There's an entire thriving economy in SF with jobs these people could be doing. What aren't they doing them? If cost of living is too expensive there, why not go to a cheaper city and do work there? If they have skills to be a white collar worker, SF is a great place to do that work and easily afford housing. Why aren't they doing it? Mental illness and drugs dominate the problem by such an order of magnitude that anything else save for harsh imprisonment to get off streets....especially subsidization of their lifestyle, will accomplish less than nothing.