Sorry Habba, but I am sure we all know loads of people with great jobs who do not have a string of extra curricular accomplishments, so it's not naive to think that happens. Moreover, most recruitment procedures these days don't put the kind of emphasis on extra curriculars that they used to, and are moving towards competency based frameworks. This is far fairer in many ways, because the student who can demonstrate insight into an industry through part time work, or work experience, has demonstrated a greater drive towards that particular role than someone who spent years getting really, really good at the banjo.
When it comes to students applying for medical school, and later med students applying clinical placements, for example, it is absolutely true that they need to show more than academic excellence, but the people who get the placements they really want are the those who are able to show commitment through relevant experience. The students with the edge are the ones who have volunteered at care homes or raised funds for Cancer Research - not the ones who play badminton at a high level.
As I acknowledged above there are some less forward thinking sectors who don't seem to have very focused or relevant ways of distinguishing between highly qualified candidates. The real trouble with this is, that with the lack of a thought through recruitment procedure, comes a tendency - as you pointed out yourself - for people to recruit in their own image, and prioritize candidates who do the kind of thing that they enjoy. Xenia seems to think that this is quite a good idea, and argues that "None of us wants to work with people....with whom we have nothing in common." I disagree with this. I know that I, personally, have worked very well with many people with whom, on first glance, I may appear to have nothing on common. More and more businesses now are beginning to realise the benefits of having a diverse workforce, and I don't think many of us would claim that this is a bad thing. So the danger of relying on extra curricular activities to distinguish candidates, is that it's very easy to fall back on looking for candidates who look like you - and it's evident that class plays a role in this. This is what I'm wary of. I'm not saying it doesn't happen - what I'm saying is that class evidently plays a part in it, and that these anxieties about class motivate this particular type of pushy parenting, and the hysteria around this kind of competitiveness actually makes things worse - and a lot of companies and institutions have a vested interest in whipping up parental anxiety about these issues and overestimating the impact they will have on a child's job prospects.
I'm not saying that the anxieties of the kinds of pushy parents are not real - but they are bound up with class in all sorts of ways - and that pushy parenting perpetuates anxiety about the problem. As to the fact that class is a covert factor in these issues, the best way to deal with it is to call it out, and be frank about it, and make it an open issue, rather than just ignoring it.