I'm not sure I understand what you're getting at. A thinly veiled insult perhaps?
It's great training, and not to be discounted. But having a haven of stability in the home is an essential counterbalance.
Based on my own childhood, I both totally agree with the premise and come to a fairly opposite conclusion: home must be a haven since it is the only place that has any reasonable chance of being a haven. School almost certainly won't be; other kids can be real assholes sometimes.
I've seen a lot of people that went to private schools really not understand just how stupid can be nor how such people think, because their world was chopped off at something like a 105 IQ floor.