Rounding up all the unemployed people, and forcing them, at gunpoint, to dig ditches and fill them will certainly increase employment, but will not do anything worthwhile for society. (I guess the ones that survive might end up in better shape.)

Having them fix potholes or educate children will increase employment, as well as prosperity. (Setting aside the obvious moral problems of the means by which this took place.)

Rounding them up and putting them into workhouses, where they build things for the benefit of a few well-connected individuals is how we have traditionally done this. It combines the worst of both worlds.

What people forget is that jobs are the means, not the end.