I feel like the problem lies in getting your feet through the front door, after that how you got your education really doesn't matter anymore. You were lucky enough to get an interview with Microsoft thanks to your past work experience, but other people (especially the ones who try academia before going into the private sector) don't have that chance and most of the time won't even be invited to an interview, that's the problem.

I am confident that if big companies actually interviewed people coming from different universities they would find that most top-uni grads are worse that people coming from different institutions who always feel like they have to perform 110% just to level the playing field.