This is the wrong counter-argument, I think. Top schools get such a number of applicants that they have to turn away a fair number of qualified candidates, and once you are in and are not totally socially inept you can't help but make the connections that will get you set for life. Luck plays a great part at this stage, even though it's anathema to say.

If anyone wants to test the tiger-mother theory they should perhaps look at people who got into decent schools and follow up how they did.