For better or for worse, that GDP boom was enabled by the massive spending and outcome of the Civil War, much like WW2. To point to these moments and ignore the immediate massive historical events that preceded it seems like a serious oversight in the analysis.
You chastise the comparison but then admit they're much alike, did you think that a complete accident. Obviously two different times are two different times but it's hilarious the hypocrisy you often see of regulatory proponents talking up post WW2 gains as the regulatory apparatus spun up -- but when you point out other post war periods with lower federal burdens suddenly the narrative changes to 'not like that!'
