FDR, by all studies, did not help, but hindered the depression from ending sooner.
"By all studies"??
What studies are you talking about??
Take, for example, unemployment:
1933 (first year of introduction of the New Deal economic programs): 25.2%
1936 (last year of introduction of the New Deal economic programs): 13.2%
1941 (when we entered the war): 8.5%
Take GNP:
1933 (first year of introduction of the New Deal economic programs): 68.3
1936 (last year of introduction of the New Deal economic programs): 101.6
1941 (when we entered the war): 114.2
Aside from this, the New Deal introduced programs that are still active today, like the Social Security system, the SEC (imagine what the financial system would be like today without any oversight what-so-ever?,) FDIC, heck, half the infraestructure in New York was built back in the 30s!
Now, we must make a distinction between what is positive for 95% of Americans and what is positive to that 5% that is not contempt with owning 75% of the shit. To those 5% the New Deal did not result in "favorable business conditions" precisely because for a brief time in American history, albeit rather reduced in scope, the American government was put to work for The People. Big Business does not like that. Period. So when talking about these economic programs the usual rethoric tends to be on negative side.
WW2 got us out of the depression, not the New Deal.
To put it mildly, what got us out of the Great Depression was the fact that we entered a war, we won it, and we virtually had a 1-billion people market "devouring" everything we made. Pure chance. Imagine we entered the war, the Japanese/German axis won and we were left without a market.