But the 100 people you would know would be biased towards Math grads, and less towards English or Environment majors, right? Survivorship bias means you would be less likely to be in touch with collage drop-outs.
What do you think the "alumni lists" on researchers' webpages are good for? On the other hand, if a researcher has no alumni list on their page and isn't just starting out, that's an obvious sign for all that can read.