On a much smaller, more intimate level, I liken this process in some ways to what I witnessed with many "preacher's kids" ("PKs", they were often called) from my Fundamentalist youth: they were so tightly controlled and directed in every facet of life—even into their late teens—that they struggled to think critically and properly engage with the larger culture. They were often given pat answers that weren't, in many cases, necessarily wrong, but which weren't so much taught as foisted upon them. There was, in other words, an approach to life that was quite reactionary and fearful, rather than confident and open to questions and debateThere are some parallels here. You would think that if a world and life view is strong then those who are closest to it and are deeply immersed in it from birth should see its strength and not be attracted to counterfeits. But it does not always work that way. PK's can rebel against the faith. They tend to be really good or really bad. But one would expect that having a strong spiritual father they would do better than they do.
Catholic societies have been generally weak. There are exceptions, Poland, the Philippines, until recently Ireland was one too. But Catholic societies like Spain, France and Italy have really not resisted liberal Christianity very well. Protestant countries like Sweden, Germany and England have not done much better but you would expect some spiritual benefit from true sacraments and a legitimate teaching authority. It is hard to see it.
So why does this happen? Olson's theory is that power can cause pastors to take shortcuts. That is they push their theology but they don't teach their theology. They arm twist people into the faith rather than presenting the full beauty of the faith and letting it attract people. So they look converted but they are not really converted. They have not made the free choice to embrace Catholicism. So it can become somewhat forced. God can seem oppressive. Intuitively they know He is not so they put the stuff they were forced to accept in a different category. It is not like being forced to accept truth about math or geography. It is personal so nagging doubts continue to bother you. But you might not be able to ask those questions out loud. You just don't feel people would respond well.
As a PK I can understand some of that. In school kids could ask offensive questions but I could not. If the preacher's son asks, "What is wrong with looking at pictures of naked women anyway?" there will be a different reaction than if a random teenage boy asks that. So you learn not to ask anything that might embarrass your father. For me that was not a big deal because I was not the kind of kid to ask stuff like that anyway. But I can see how some people might feel they had questions that there was no forum in which they could ask them.
So the thinking is that when religion becomes entrenched in society the fear of questioning can be widespread. Especially when it becomes associated with political movements or ethnic communities. Rejecting Catholicism becomes unthinkable on grounds that have nothing to do with religion. So even seriously questioning it is out of bounds. So nobody struggles with the hard questions in a good way. That leaves an invisible weakness in people's faith. As soon as the non-religious reason for being Catholic is removed then that weakness expresses itself.
I have posted previously on Belloc's explanation for the rise of liberal Catholicism. His focuses on intellectuals. Olson's theory, borrowing from Wiegel, really applies to all Catholics. He emphasizes the importance of clericalism in associating the church with something other than the faith. Belloc talks about anti-clericalism as a big factor. It seems like a contradiction but perhaps not. People tend to go from one extreme to another when they see a problem and overreact.