I absolutely have gotten industry jobs through my work network and, doubtless, through where I went to school to some degree. But basically zero of those have been through people I met in school. The school network aspect is almost certainly overstated in most cases. I've never gotten a job offer through a classmate or college professor.

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.