I think there's also the possibility of folks who go there are self selecting for ability, connections too.
I kinda suspect somewhere out there there there might be some backwater community college that actually improves the prospects of some rando students by a greater % than some fancy college with high achieving student's whose prospects were already pretty amazing... that doesn't mean you can replace one with another but that the situation has a lot of factors to consider.
Dude I knew who went to Notre Dame often talked about how it made him very successful. I kept telling him "Bro you're the smartest guy I've ever met ...." (dude was amazing). Finally years later he came around to a similar conclusion. His success was smarts and happenstance (he picked some good companies early on), Notre Dame was a good bonus / certainly helpful, but a lot of other factors were at play and was more of a factor of him being smart enough to earn his way into such a situation.