Instead, everybody is just saying the same thing expressed in different wording - safety.
His point is not to bypass the entire family, house aspect of your life. The point is to not move along life as if you have no choice but to move to the next "stage".
Progress is not moving up the stages - getting a house, getting a family, a dog, a kid. Those are just arbitrary checkpoints defined to make you feel like you're making something of your life. The american dream, eh? :)
Progress is to construct a life not defined by limits and boundaries. Living it to the fullest - travel, do great big, inspirational things.
If you choose to have kids when you're 20, you are almost by definition limiting your life only to be somebody who takes care of your kids and works a stable job with a stable family(a stable car, a stable dog, a stable bed to sleep in, a stable tv and a stable view of the world). In other words, inexperienced and short-sighted.