I think the point is more that most of the hard work behind Twitter isn't in writing the "fancy" code at all - it's in developing the infrastructure that allows

I think the point is more that most of the hard work behind Twitter isn't in writing the "fancy" code at all - it's in developing the infrastructure that allows that code to safely propagate across Twitter's massive network of servers, and abstracting that complexity away so that the developers who make the "fancy" user-visible changes don't have to worry about it.