For young children (that is, before entering school), children are often at home all day being cared for either by a parent or a nanny. If you don't have a separate area to work, it can be really difficult to explain to your kids that Mommy or Daddy can't play because they need to stare at a screen for hours.

I think they are trying to say that in higher cost of living places you sometimes cannot afford to have a space large enough for your family and your work space. If they work at an office maybe their life partner takes care of their family during the day.