The benefit would be discouraging people from having kids they can't afford and not forcing employers to pay employees who aren't working.
If you want to get paid for work you're not doing, you should at least have a conversation with your employer about it.
You bring up an interesting point about efficiency, and regarding most other things, I would agree with you, but your employment is one of the most important things in your life, so it's worthwhile to do the work to understand your contract.
Perhaps you haven't noticed, but all the evidence would suggest that that isn't working. You can't just not pay people and they magically stop fucking.
Rather, the framework is broken. When we hyper-individualise everything, we end up with a world people can come to frame thoughts like the one you've expressed.
A world where everyone must own one of everything, and a spare, in order to survive. Where betterment is defined as having more and better things to throw in the garbage heap.
So that future archeologists may dig up our society and find the last of the great cetaceans, beached, with their bellies full of custom gift cards with your face printed on it.
And that is a sad state of affairs.
The more educated people are the fewer children they have. And we continue to price more and more people out of education because they lost the birth lottery.
Yes, we can expose the reality that most people aren't economically worth enough right now to demand parental leave or living conditions, but what is the benefit of exposing that?
It's not like figuring out the true price of a product is low because it's low quality, so if people stop buying it then the producer will stop making it. The people that aren't worth enough, whether it be because they are lazy, stupid, came across an illness, born into a poor family and never had the opportunity and mentors to teach them, should we just let them rot away?