Nobody did. At my ex-employer, I did an informal survey, with a simple reformulation of the original question: "Would adding developpers to a late project help or not ?" Everybody answered yes, even some people that DID read The Mythical Man Month.
So, if six months down the road, you need more dev resources because you're falling behind a little, adding some of those devs back will probably help speed things up. Notice that the company that added the devs in the story has 400+ heads already. What they could be doing is hiring new guys to take on some of the non-exchange related work they were doing and shifting some project-experienced devs back on.
Of course, that's the best possible scenario. What they're probably gonna do is just fuck things up.
(Note the smiley on my comment).