Paradise - that's a bit of an over-simplification. It's not about having a mortgage or not, in the same way it's not about benefits or income or anything. It's simply about emotional/time/practical/financial investment in the house.
There is a link between how long someone remains in a property, their roots in their community and how well they maintain their house. They have a vested interest. People who buy rather than rent (BTL excepted), tend to have longer occupancies than tenants. Long-term HA tenants also have that vested interest. On established estates many of the elderly tenants remain from the days when it was the norm for all but the well off to live in council-owned property, when there was no stigma attached.
Many new builds simply don't have that investment of commitment because they have no history, so they rely on people's investment in the property. Those who qualify for HA tenancies these days usually have a significant 'need' in a way that wasn't the case years ago. Drug addicts, for example, will be prioritised over a couple with no dependents. If you get the single mother or couple who has been patiently waiting for a 2-bed house, you'll be on a winner. If you get the drug-addict who likes to move regularly to escape the bailiffs, you might feel differently.
There are no hard and fast rules. Every tenant/owner is an individual just as every estate is unique, but there are trends.
I would never buy a house on a new estate, whereas I'd happily buy from an established community. I don't give a damn about whether people own/rent work/claim benefits. I do care about crime and anti-social behaviour.