Not to say that I think that giving a homeless person a home will magically solve all his or her problems, but how does giving someone an apartment isolate him or her in a way that being on the street does not? (It's not a snide question; I've never been homeless, and maybe there's a stronger community than I see—but it seems unlikely that that community can provide the real mental and physical care that such an afflicted person would need, and that the people who can provide it find it easier to ignore a dirty person on the street than their next-door neighbours.)
In those places a lot of voluntary help is given, workers chat to you, sometimes you'll even be given some new clothes, but nearly always you get to interact with others.
I cannot emphasise how hard being homeless and without a network is. You have no-one to talk to ever except for these people who by necessity you come into contact to. I also cannot emphasise just what happens if you have too much time alone and yet live in fear, hunger and with some problem (mental health, an addiction, etc).
Some of the people I knew from the streets wouldn't have survived in a house. They needed their contact as much as they needed their next drink, it was all they had and the only thing that prevented them from losing themselves totally.
The isolation from giving them an apartment is that no-one will visit, and if they do then not enough.
And the problems they'll have are worse and will go to basics such as hygiene. On the streets they never had to clear litter, pick up dirty clothes, and clean their environment... they would just move on if it was bad enough. In a flat most of the people I knew I believe would've just rotted and allowed the space around them to become full of junk and to also rot.
They'd need to be taught how to care for themselves. How to cook safely. How to budget and make money stretch (there is little thought of the future on the street, you spend what you have pretty quick in case you lose it. You wouldn't think of bills and taxes).
And to learn those things you'd need them to have sound mental health, alertness, awareness of their surroundings. You'd need to help them to shake off their addictions, and to respect themselves. You'd likely have to counsell them and provide support for mental health problems.
And if you achieved all of that. Then they would be devastatingly lonely. They won't have what you take for granted, there are no friends for them to call upon, family to visit, money to go sit and bar and chat. They'd be alone and desperately wanting to rid themselves of that loneliness.
In all likelihood they'd go back to the streets where they have contact, interaction and community. Where they didn't have to put in all this effort to care for themselves when apparently that amounts to loneliness and isolation.
It takes far more than a roof to stop someone being homeless. Homelessness is a state that encapsulates far more problems than just the lack of a house. To solve it, you need to address all of those problems and not just the lack of a roof.
Today we've pretty much solved the basic home problem in the civilized world. Perhaps not 100%, but nothing is ever solved 100%. What's left are the hard cases, which is what you are describing. Our cultural attitudes haven't updated for this fact, and so when people hear about the homelessness problem they naturally think the problem is simply... homelessness. Unfortunately it's a harder problem than that, and we make it even harder by misunderstanding it.
Today we've pretty much solved the basic home problem in the civilized world.
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Some data on American housing and such, that may not be 100% accurate but should paint a general picture:
Around 60 years ago, the average new home was about 1200 sq ft and housed a family of 5 (2 parents, 3 kids). Today, it is over 2000 sq ft and houses a family of 3 (2 parents, 1 kid). This difference and other factors has helped create a widening gap between the haves and have-nots: Those who can afford a new home live like kings. Those who can't may be perpetually one paycheck away from homelessness. Most of the financing instruments we have are aimed at single family suburban homes designed to meet the needs of a 1950's-style nuclear family. Meanwhile, our demographics have changed and very few people fit that bill. The housing industry has been terribly slow to adapt to the changing needs of our changing demographics.
Also, historically, it was more common to live with extended family. This was more manageable back when more than half the American population lived and worked on a farm. You could always put someone to work on the farm to help cover the cost of feeding and housing them. But a more city-centric lifestyle means that if you have no job, you typically aren't viewed as a contributing member of the household and it is much harder for people to extend generosity in that regard unless they are truly wealthy. We also had more SRO housing and boarding houses -- just the sort of supportive environment that the Murray's of the world seem to need. This was part and parcel of the culture and was not considered some kind of "special service" for problem individuals who couldn't adapt. It was also cheaper than a stand-alone apartment. Apartments designed for a nuclear family or houses designed for a nuclear family make up the majority of housing stock in the US and it is financially out of reach for many single individuals. College students often get multiple roommates to make it work but it really isn't designed to work for them. The Murray's of the world lack the ability to force the current housing situation to serve them adequately and mostly don't have other options which did exist not that many decades ago.
I have a lot more thoughts and information on the subject but I don't care to beat it to death. The current housing situation really is a factor in why homelessness has been on the rise in recent years. Yes, it is one of many. But I don't think it can be lightly dismissed.
You mentioned contact and community a few times there - do you think that dealing with full homeless communities, or at least a subset of 5 to 10 people, would be more successful than trying to deal with individuals? Do you think that choosing a group of four homeless folks and moving them into either a single apartment or neighboring apartments would wind up having a greater chance of success? Or do you think that would perpetuate social norms that are nonconducive to more survivable lifestyles?
Take this as a component of any particular aid approach, by the way - there are no silver bullets and a lack of a roof is often a symptom of many other problems that can't be solved by craigslist's housing section.
