I'm not convinced you understood the comment you replied to, which doesn't suggest placing a public park in somebody's yard. It suggests that people are clinging to their yard when they could instead have a housing option which doesn't have a private dedicated yard, but does have a much larger and nicer public park nearby which serves that need for green space.

And honestly, if a person wants to make a little public park in their yard... I don't see what the issue is with that? But yeah, that's not what was suggested in the slightest.