Both the Civil War and the Great Depression required more governmental involvement than had been the case. The former because of the defense of the Union and the latter because of the demands of the electorate because of the collapse of the economy. Starvation tends to overrule theory in such cases. The man who has no job and no food for his family does not really care what the economic theorists have to say about the negative side of government feeding the hungry. Roosevelt faced very real possibilities of real communist uprising and was not even the most Left of this party. He did not initially make major changes in fiscal policy even going so far as raising taxes to balance the budget.
Only after Keynes had laid the theoretic framework for governmental involvement in the economy did he move to implement the New Deal. Then he showed once more how popular Class Warfare is to the American voter.
Any complaints about the size and nature of the US government should go to the American people since its change has been with the full approval of the majority of them. Until they have been re-educated to more conservative views it is pointless to run far Right candidates for national office. Bush is about as far as they will accept and just barely that.