The huts were cheap, and being self-contained they were good tools to help someone re-enter the world of housing, of taking care of housing, of cooking for oneself and cleaning, etc. Training grounds for all the skills you need to survive when you finally get somewhere larger, but also large enough not to give you shelter, security.
They had other things, like a central place to go and socialise, to get used to humans again, and counsellors and support people... but the key thing is a very small space that is yours.
That would be enough... a shed.
It need not be permanent, just enough to lift someone from the very lowest point in their life to a point fractionally above that.
In effect I did this too. For shelter from snow over Winter I would trespass onto building sites after they had closed and would sleep in the site office. It was shelter, there was generally a heater and a kettle. I could make a bed, I would leave the place tidy. But most of all, it was safe and I always felt confident I would survive the night (something I wasn't sure of the times I lay shivering violently under bushes in Manchester).
Little steps, lots of support, understanding. Just giving someone an apartment isn't the answer, it's about supporting people, to help them re-integrate. A home isn't a magic bullet for people not ready to live in one.