When I think about economy of scale and software development, all examples I come up with have the property that any gains are diminishing quickly. For example,

When I think about economy of scale and software development, all examples I come up with have the property that any gains are diminishing quickly. For example, a large system has a better build system, which catches a higher number of bugs, therefore the developers are more productive until the now larger project eats the added productivity due to higher complexity. On the other hand, what in traditional industries would be called production, that is producing the specific website for one request, has a rather absurd economy of scale. With a single server and a static site you can serve a sizable fraction of the world population, with negligible marginal costs of serving an additional user. Actually Metcalfe's law suggests that the marginal cost of serving an additional user is negative and hence we get the behemoths like Google and Facebook instead of competition of a few different corporations.