i got my first industry job through interview performance, but in later job transitions my university affiliation ended up playing a major role because certain employers are extremely focused on certain feeder schools, at least for periods of their existence often through founder bias or because it buys a certain kind of harmony based on shared experience and shared world-view.

Atlassian’s founders are two college mates - one from rich background, one who couldn’t afford a computer until 12. One example of a multi billion dollars company offsets the idea.

Sure. College mates start companies together. I'm friends with a bunch of people who started a now defunct gaming company more or less out of school. I know others who basically got their jobs because people they knew from undergrad activities were editors or whatnot.

But there's this mythology that the main reason you go to Harvard is to network with movers and shakers isn't generally true in the main.