They may encourage as much as they want. I can spend my money on rent if I choose(or live under a bridge and spend it on Mad Dog 20/20 and understand the universe a bit more). However, when they take my money, I lose control of it.
What is the difference if you and a few million others choose to spend your personal discretionary funds on cars and red wine or if the funds are concentrated and the system chooses to spend the pooled resources on cars and red wine?