Russ Roberts asks a good question here.
Which is best for stimulating the economy? 1) If you have a bunch of unemployed carpenters, drop a bomb on a big city (evacuate the citizens first and put them up in rental homes), then employ the carpenters to rebuild that city. 2) Just give the unemployed carpenters the amount of money they would have earned working, but don't destroy the city. 3) Figure out why there are so many unemployed carpenters, then address that.
Many Keynesians argue that number 1 is the best idea. Roberts, and I, disagree.