I don't think that's a counter point. I'm not saying that CS masters people can't be successful employees or entrepreneurs, just that in my experience the ones I've interviewed tend not to do well on simple "implement this function" type questions. I'm not making a broader claim, just stating my experience.
It is a counter-point to "I always cringe when I have to interview someone with a masters degree in computer science", because there seems to be a generalization encoded there that people with master's degrees tend to be weak at interviewing and weak on practical skills (based on the rest of your comment).
