Context is important. That was under "Where Should You Post Your Internship?" - yes, if you're limited (by budget, time, etc.), it makes sense to target people who are even marginally more likely to work out.
That doesn't mean you have to go to one of those schools to get in - which school you went to is treated as a weak signal in the resume reviews, and is ignored for the rest of the process. I went to a public school that falls outside of the 30% rule, for example, and another from my school will be joining us this summer.