This is true of an idealized perfect free market with perfectly rational consumers, but not so much in the real world. The simple fact that profits on phones haven't been competed to zero is enough to show it's not a perfect free market. I don't think the average consumer spends much time considering the long-term health of the app ecosystem when they purchase a phone. Maybe the wisdom of the crowds is correct here and it's truly not important or beneficial, but to me it seems more likely that it's outside the bounded rationality of most consumers. Markets have blind-spots and they tend to be short sighted.