Constant returns to scale (CRS) is one of the corner-stones of the competitive general equilibrium paradigm of neoclassical economics. This note argues that the equilibrium solutions of this paradigm are not compatible with CRS. CRS implies that all producers (whatever their scale of production) can produce goods at the same unit costs: and this makes self-production a feasible alternative to market production. In the event, an infinite number of equilibria become possible with a mix of markets and self-production. If labor is the only factor of production, self-production becomes the only option: and the market economy ceases to exist.