I think this is a strange attitude we in the west have developed. For most of history, children were the retirement plan. You needed them to take care of you. So the idea of them paying rent just didn't make sense. They were helping you farm or produce food, goods. So I think this attitude is not wrong but it's not complete. A family supports each other. Not just oneself.
Discussion
I definitely agree with this, how you treat them is how you will be treated when you're old.
Supporting your kid if they and letting them move back in if they’ve tried and made ends meet but lost their job or something until they get on their feet is one thing.
If they’re unwilling to get a job and just want to sit on their asses freeloading is different.