And what of those who don't have a "spare house" but are renting out to keep hold of their property with the intention to live in it again in the future? Someone who goes to work abroad for a couple of years, perhaps? Or someone who outgrows their property due to having kids, can't afford to move up the ladder, wants to keep a foot on the ladder and maybe move back to that house in the future so they've got a roof of their own to retire to? Or people who own a property they rent out in a cheaper area, and then live (renting) themselves in a more expensive area, where they have no hope of buying, but still want to hang on to the property, so they have somewhere to retire to one day?
I know people for whom all three of those categories above would apply. These are not hypothetical scenarios I've plucked out of thin air to be contrary. Your assumption that all landlords are privileged people with "spare houses" is simply not true.
I will happily treat lack of social housing as a priority issue when I decide who to vote for, and then hold politicians to account when election promises on this point are unfulfilled. If you are a landlord, you obviously have an obligation to treat your tenants fairly, and that in my view means giving them more than the two measly months notice the law requires (really, I think landlords should honour the entire duration of an assured shorthold tenancy. Tenants quitting tenancies early is different as it is generally much easier to find a new tenant than a new flat!) As a private individual, and not a housing association, that's where your moral obligation in this situation begins and ends, I'm afraid. I don't think it extends to asking people to ignore guidance from letting agents about which tenants do/don't pass their affordability criteria, or expecting them to accept below market rent in locations where HB wouldn't cover full market rent, or taking out more expensive mortgage products/landlords' insurance policies just in case one of your future applicants for a tenancy at your property happens to be on benefits.
PS nobody is "pissing all over someone at the bottom of the heap", all we are doing is repeatedly asking someone to stop calling us vile, disgusting, money grabbing scum, wishing bankruptcy on us and telling us to fuck off and die! Which, let's be honest, is hardly unreasonable.