You are not a typical student from an unranked college. You are an outlier in terms of your drive at your unranked school, and if you had attended MIT, your drive would have been an outlier there as well.
That is pretty much how entry level jobs work across other industries as well. As blevine said above, it is all a matter of who gets the job. I firmly believe there are far more smart people outside MIT and the Ivys than inside them, so it should surprise nobody that a company like Microsoft will have a mix of people from many colleges. The other reason is that many MIT-level students are finding higher paying jobs outside of tech firms.