Again, this is nonsense.
By far the largest shortfall in social housing in central Scotland is one bedroom, single occupancy properties. This has only been exacerbated by the surge in buy-to-let snapping up any small flat that hits the market and driving rents up the point whereby young people can't afford private rent.
Young people without children do not qualify for offers of multi-bedroom properties in the first place, because they do not have dependents, so priority goes to those who do.
The way to solve this is either
Kick people with children out of their Social Housing properties in order to free them up for more "responsible" people who do not have children, and ignore the fact this renders children homeless.
or
Build more social housing, which you've already stated you believe is part of some nefarious SNP plan.
Your assertion that young "responsible" people will never "get to the top of the list" because of irresponsible people with children is nonsense, because the two are not eligible for, or competing for the same properties, so they are not on the same "list" to begin with.
If anyone applies for social housing and waits long enough, they'll get offered social housing. The long waits are because of a lack of availability of all types of social housing, but it simply is not true that people with children force "responsible" people to wait longer or deny them housing in the first place, because the two are not in competition for the same properties.