Raising children simply takes time and energy, and turns you away from other activities. If I had to take them to and back from daycare, to spend 3x the time needed for every activity because they're a very inefficient part of it, would I still have the willpower to cook everyday, to make my commute on bike, to live simply without much stuff or furniture, to do 2 hours of exercise daily (not much for the environment, but still keeps you in shape)...

Considering the situation of people that went that way, one can doubt it.