I highly dispute this. Networks in college are absolutely a thing and absolutely advantageous. In my experience, the network didn't come from just sitting in class, but from extracurricular competition engineering/cs teams. Competition teams certainly helped many people get their first jobs through friends referring each other or elevated exposure to employers. In fact, recruiters would often have separate hiring events for the competition teams and then have the standard college hiring event. There's also an intangible effect from being surrounded by other highly motivated and mission driven students that you gain in these environments. I am sure there is a way to get involved in similar teams outside of college, but a well situated college significantly lowers the barrier to joining these teams and almost creates a funnel for it should you choose to spend your spare time in such as team.