F451 - they were not "given away" they were sold, to long-term tenants who in the main part would have remained living in them whether they continued to rent or not.
RtB is not the cause of the lack of sufficient supply today - lack of new provision to satisfy new demand is the cause of that. Since existing tenants are part of existing demand, and converting them from tenants to owner-occupiers reduces existing demand by exactly the same amount as the reduction in existing supply, the net effect on availability for new tenants is ZERO, as I have explained to you numerous times before.
It would not matter whether you have two million or ten million additional social houses in the existing stock - if they all had long-term sitting tenants in them their houses would not help new families in need of housing. That need can only be satisfied with additional housing construction that is proportionate (but not equal) to the demand.