Basically, that's the broken window fallacy...that artificially making people buy a good or service they don't need, in an effort to create growth or jobs, is worse than letting people buy the goods or services they DO need.
That's a very good argument against Keynesian style stimulus.
But I want to take it even further...
I'm saying that even if the buying activity (consumption) is done completely freely and the purchased goods ultimately ARE wanted by the consumers, I still maintain that the consumption of those goods does not stimulate the production of them.
Our ability to produce more does not come from increased consumption, but by getting better at production, which takes time, work, research, and technology...and under-consumption.