Hostels are not for free they want money from someone either the Service User or the Benefits System.
They are also full the the brim bedwise 99.9% of the time.
Their are a lot of very scared people living on the street, they fear judgement/change/shame and loss of dignity more than the cold weather.
As Wanted said its not just about putting a Roof over a homeless persons head, its about people seeing them as a person and approaching their life struggles/issues working in a mutually understanding way with them to improve their lives for the better longterm.
you can house someone but unless they get the right support the chances of life improvement may deminish in a short space of time.