Competitive coding, despite superficially involving typing code into an editor, has almost nothing to do with working on large pieces of software. It's a lot of rote memorisation, learning algorithms, matching them onto very particular problems, and so on, it's more of a sport. Just like playing too much bullet chess can be bad for your classical chess I can honestly see how it gets into the way of collaborative work.
It's easy to make generalizations that minimize or downplay some of these things. But it's no more knowledge then the original study on too little data was.