My knowledge of social history is not sufficiently detailed to take this without some suspicion (although those on the other end of the political spectrum will no doubt dismiss it without consideration). There may certainly be a significant “yes, but” required in the assessment of the period in question, but this strikes me as something that ought to be remembered:

In the 19th century, even though capitalism had only existed for a short time, and had just started putting a dent in pre-capitalism’s legacy of poverty, the vast, vast majority of Americans were already able to support their own lives through their own productive work. Only a tiny fraction of a sliver of a minority depended on assistance and aid–and there was no shortage of aid available to help that minority.
But in a culture that revered individual responsibility and regarded being “on the dole” as shameful, formal charity was almost always a last resort. Typically people who hit tough times would first dip into their savings. They might take out loans and get their hands on whatever commercial credit was available. If that wasn’t enough, they might insist that other family members enter the workforce. And that was just the start.

Although it may have amplified important principles that already existed in the culture, a reasonable historical analysis could find that progressive governance merely happened to coincide with the prosperity of 20th century America. Indeed, certain of its initiatives have arguably hindered economic and social advancement, but because of the way they overlap in history, we’ve come to feel that big, minutely involved governance has a causative relationship with that which was good in the past dozen decades.
Of course, even if there were some truth to that feeling, the next questions are whether such government will inevitably lead to circumstances such as we currently face and whether our circumstances truly do herald the collapse of our society. If both are the case, then a good half-century is hardly worth the cost.