The thing is that you frequently end making connections with alumni of those institutions in your first few corporate jobs, since they all recruit out of the sa

The thing is that you frequently end making connections with alumni of those institutions in your first few corporate jobs, since they all recruit out of the same pool of elite universities. So even if you didn't go to Stanford or MIT, if you work at Google (well, in the 00s - it doesn't focus nearly so much on elite universities now) you will know people who went to those schools, and if you need to make a connection with another alumnus of them you can reach out to your friends and say "Hey, can you connect me to your classmate?"