We absolutely need to build more subsidized housing. And I support those policies, including many of the perennial bond measures. I do so out of earnestness and the hope that the next bond measure will placate the various NIMBY factions on the Board of Supervisors. They disappoint every time, but failure would only truly come when I and others like me give up on sincere attempts at compromise.
But we (San Francisco, Oakland, etc) can't build ourselves out of the homeless problem. Our problems and their causes are multifaceted. In 2004 Mayor Newsom committed San Francisco to that very solution with a 10-year plan, and by 2014 it had acquired or built a long-term residence for every chronically homeless person in 2004. Approximately 3,000 units for 3,000 people. See https://sfmayor.org/sites/default/files/FileCenter/Documents... Chronic homelessness was near a nadir. However, over the next several years homelessness exploded even though in terms of economic inhospitableness nothing had appreciably changed since 2014.
As a child we moved all over the place, town to town, state to state, chasing better jobs and cheaper living, with varying degrees of success. Poor people, even with empty pockets, are resourceful and somehow manage to get around. Some are better at it than others. This phenomenon is especially stark in accounts of genocide, where some people are seemingly unable to fathom relocating even when they have the economic and physical means and despite knowing their death is imminent. But the operative word is some; some can't, but some can. (Neither the poor nor even the homeless are a homogenous group, and much is lost in our--including my own--reductive aggregations.) It would be patently inhumane and unreasonable to pick any homeless person on the street and demand that they move away. On the other hand, policies that assume as a general matter that the poor or homeless can't, won't, or shouldn't relocate in search of better opportunities or conditions are sorely misguided, not to mention doomed to failure when adhered to at such a local level.
Moreover, from a purely accounting perspective, neither San Francisco nor Oakland have the resources to mitigate all the economic pressures for housing. For definitions of "affordable" bandied about by many on the far left, if you crunch the numbers (e.g. $500k per unit, which is somewhat conservative) San Francisco would need to spend hundreds of billions of dollars to build enough subsidized housing, and that's if the situation remained static. That's not remotely realistic even though the City of San Francisco already enjoys the highest revenue per capita of any major American city. To think Oakland, a far less wealthy city, could merely build its way out of the current problem using public funds and without displacing anybody is even less realistic, to say the least.