I agree with your analysis of the so-called "greatest generation." But you're mixing up the causes and effects in terms of this discussion. The point is that when these people were children, the adults of that time were able to inculcate the faith in them. Later they lost the faith and went haywire after Vatican II.
But the Church of the generation who were adults when the "greatest generation" were being educated believed that their goal was to teach and sanctify every Catholic. They were seeking every soul. They did not assume 100% failure as the de facto standard, and then rejoice if even 1% succeeded.
The approach represented by the author of this book would be like the Good Shepherd who sees his 100 sheep wander away, and then rejoices because 1 sheep found his way back into the fold.