If landlords en masse chose to sell their properties because they object to providing decent accommodation for a reasonabler amount of time and at a reasonable rent, then the market will be flooded with properties for sale.
That, admittedly, won't be the greatest news for people who are buying, or who own, their homes (as I suspect many older people do, including myself), because then property prices will fall. But it will mean that younger people will have more chance to buy a home instead of paying extortionate rents.
At the moment, those extortionate rents are, in many cases, being part paid by taxpayers through housing benefit. In my opinion, a far better option is to return to providing council housing for those who cannot afford to buy. Council housing is a public asset whereas paying housing benefit to landlords has no benefit to anyone but the landlord.
Not all landlords are greedy and negligent but there seems to be a significant number who are. I have no sympathy whatsoever for them and if there are any gransnetters who do, I assume they are not stuck in expensive, sub-standard accommodation with the threat of eviction hanging over them if they ask for essential maintenance to be carried out.