Why is this? Is it partly influenced by the fact that LinkedIn etc suck?
The interesting thing is people recommend "networking" and people think it's like... meeting people at industry events or reaching out to linkedin connections but that's not really how I see networking working in real life. The networking that actually gets people jobs is networks from people you've already worked with before, or your professor is on the board of the company or like.. your parents know the exec team really well etc. So new grads truly are disadvantaged.
I say the are three levels of "networking", and peeling back the layers helps to understand why the term can become so nebulous
1. "Associative" networking where you reach out to people at your old school and work but people you otherwise never met nor worked alongside. They vouch based on what they see and know about your associations. They might refer, but often can't do much about the process but poke at the machine.
2. "familial" networking where you reach out to friends/colleagues you have worked with and can personally vouch on your behalf. They might be able to help churn a bit, but are ultimately still beholden to the process.
3. "Influential" Networking where you do either #1 or #2 but your network evolves into leadership, management, and founders. People who have the ability to actually hire you. Often cutting through the HR cruft itself.
3) is what you want, but fundamentally isn't different from 1) and 2), except in who you know. You invest in 1) and 2) in hopes that they become 3) farther down the line, but for a new grad that investment will take a very long time to occur. Reaching directly out to 3) is hard for many reasons (some professors being an exception. Hence why certain schools can be so impactful), so it's often not an option at the new grad level, since you lack any real leverage to bring to the table. If you have the ability to contact them at all.
E.g. under traditional hiring you only do a background check at the end - this means there are implicit decisions being made that nobody calls out explicitly during the process.
The reality is any person in an org actually has to act in the interest of the shareholders - people who are lower down the totem pole do what their manager says - but the manager of a manager of a manager is held accountable by the shareholders via the board. Shareholders want who is the best person not who is someone's preferred hire (which can be for reasons that have nothing to do with productivity). If there was a way to enforce this - you can bet they would.
Essentially what I'm saying is, because the existing systems suck we fall back on mechanisms like this.