That's an interesting theory. I think there are competing interests, though. Landlords and businesses generally won't want homeless people in their areas, though, because their presence alone will decrease property values and rent (landlords), and drive away customers (businesses). But for what you suggest to work, homeless people need to be visible.

Do you have any data on this? This doesn't really pass the smell test for me, even though it potentially sounds like a satisfying explanation of part of the problem.