Too many Eevee's everywhere = non-excludable good = impossible to monetize.
Wut?
If there's a ton of something readily available for free, why the hell would people pay for it?
High supply of something, even with a decent demand = low prices...even more so if it's available free. Basic Econ.
Damn, really ya'll? It was an exaggerated example to illustrate easy ways to make money off the game. Instead of acknowledging the point you want to focus on the random pokemon he chose? There are a lot of them, which is why he chose it as his example, for dramatic effect.