It's been tried in SF. If my memory is correct, the city spends around $60,000 per homeless person per year trying to help them (the current year's homeless budget is $241 million http://www.sfchronicle.com/bay...). In many cases, when they were simply given homes they then proceeded to trash them and make them uninhabitable (ie condemned). They were then back on the street again, and more money had to be spent making the home liveable again.
The issue is that the homeless in SF are either mentally ill, addicts, or both. You can give them homes, but if you don't treat the underlying issue you're just throwing the money (and homes) away. But when treatment is a requirement for housing, they walk away and go back to living on the street. So what's the solution?
Many of the people simply don't want help and would rather live on the street. Just the other week, one homeless guy who camps in the doorway of my building drank all day until he passed out. An ambulance was called, he fought them, but they ended up restraining him and taking him to the hospital. Two days later he was back again. The following day he was again passed out and unresponsive in the street, and the ambulance came again. Repeat a few days later. It happens a few times a week with several people, and this is just in front of my building across the bridge in the Oakland/Berkeley area. San Francisco is worse. I can't count the number of times I've seen people shooting up. So do you force these people into rehab? Arrest them? What's the solution? Simply giving them a home won't work.