For this theory to be plausible we need to imagine that hedonistic creatures couldn't find anything more hedonistic than caring for multiple kids before industrialization. It doesn't sound realistic, mildly speaking. The modern culture simply doesn't oblige you to marry, and procreate the way it did 1-2 (depending on where you are) generations before. In the times of my mother's youth not marrying before 25-26, and not having at least one kid before 30 could really negatively affect someone's social standing. There are segments of modern West where culture still prioritizes procreation (like Orthodox Jews you mention, or old school Catholics) and they do procreate successfully despite being the same creatures as everyone else. Preferred hedonism is in culture, not nature.