I don't know about Scotland or NI but in England and Wales priority groups for housing include disability.
In most areas, you can't even get on the list unless you are in one of the priority groups.
Being in receipt of disability benefits won't automatically entitle you to social housing but it would be virtually impossible to access housing on the basis of disability without it.
Plus. disability benefits do increase the other benefits you're entitled to including housing benefit, council tax benefit so the state will be picking up more if not all of the housing costs for someone in rented accomodation.
Plus travel benefits including vehicle tax discounts of up to 100%.
Student bursaries, disabled students allowance and so on.
They're passports to lots of other things, it's not just the income they provide in themselves.