Cost effective doesn't mean cheap! It could be still high in cost, it's just the most cost effective method available.
Even if it is forged and then CNC finished, the high cost would still be incurred, Dies would need to be made (not cheap) and then still CNC machined after (not cheap).
CNC machining itself can be an efficient way of producing things, it will never be as cheap as producing things from a straight tube or as Mark was pointing out with the drop outs, from smaller CNC parts. CNC machining is expensive if doing small batch runs, there's high material wastage, high operating costs from the machinery itself, to setting it up and paying someone to operate it for the long periods of time it would take to produce some of the components Koxx manufacturers.
High volume simple CNC parts are cheap, Low volume, batch production, intricate CNC parts are not.
I don't understand why someone can't grasp why Koxx frames are expensive! They're designed and produced in for the high end of the competition market, from the best materials available, to an incredibly high standard and are very well designed. The detail they include, quality of production, production methods and materials used coupled with the very low volumes produced for a small portion of a very small market mean they have to carry a high price tag to make them a viable profitable product.