You assume the goal is to move out, but it might not be. Extended families have lived together in many parts of the world throughout history. Expectations of living alone are relatively new.
That's true, but there were also no stories of adult children getting married and living with their spouse/children with their elderly parents. There weren't even any mentions of adult children (or their parents) who sought such an arrangement.
Interesting anecdotes, but what does this have to do with the fact that the journo apparently couldn't find a single person/family who was seeking this sort of setup, or who let alone taking it to the next level? They were all just single people living at home, with no spouse or kids.
We should aspire to increase our quality of life, but keep perspective on what are new problems and crises, what are old problems and may still be unsolved. Cheap and abundant housing supply for everyone to live alone is and old problem and unsolved.