Not myself, I moved out soon after turning 19 (and finishing school)
And that´s fairly common in Germany, too.
Honestly, no matter how much I (will) love my children, I would not want them to live in my house past 20 unless it is unavoidable. I want to see them on their own feet, experiencing freedom and the responsibitlty that comes with it once they become an adult. It is also considered as moving on to the next step in live for the parents, regaining more of their freedom again. Like, I would be looking forward to visiting my grown up children and vice versa, learning about them as independent households/families.
That said, I am also fascinated with other cultures where a different, more community kind of living is cultivated. I can totally imagine if I had grown up in such surroundings, I would be more comfortable with more generation housing, families staying together longer - and I can see the benefits of such a tighter knit (? at least for physical distance) family. Without fail we need to socialise a lot as humans andthe immediate family can provide a lot of sense of community.
Maybe our cultural understanding where I life or will live will be different int he future; or maybe my own perspective will change in the future - I wouldn´t think that would be bad, as long as it´s genuine.