It's not completely wrong but it's not right either. Under FDR the American government took on a lot of reforms that would help the American people. While it's true that the amount of government spending and new employment supporting the American war machine was extremely helpful for the economy these reforms also helped significantly. FDR spent a lot of money not just on the war machine but on public projects that would provide employment for people. It's worth noting that while FDR was not formally educated in economics he still managed to contribute to the economy. He realized that the American people simply didn't have money to spend and so the economy shut down. He knew if he could get the American citizens spending money the American economy could gain strength. Before his administration the American government wasn't very concerned with the economic well-being of its people but under FDR's administration that changed.