How tf do referrals *ACTUALLY* work?

Something that's been itching at me for a while - after you talk to an analyst, what actually happens when they "push your resume". Specifically for banks where there is a decent alumni presence and a structured process for your school (firm presentation, etc). Recently I had two conversations with alumni analysts at an MM that I felt went really well. Both offered to refer me to coworkers, etc...

But I still got passed up for a first-round interview. now granted, the second convo was the day that selections were going to made according to Handshake, and they didn't seem to know much about the interview timeline when I mentioned it.

In contrast, I also got an email the same day from an EB that I did ZERO networking with (reached out to probably 5 or 6 bankers and got no responses) notifying me that somehow I DID get a first round interview.

So for people who currently work at shops that actively recruit at your undergrad - how does the process actually work? Do all the alumni of that school sit around in a room and go thru the pile like "nope", "yup, that kid was cool", "yea that dudes a dick fuck him". Or do the analysts just email HR if they feel like it and say "yo i talked to this kid, i like him" and then they decide who gets 1st rounds on how many bankers mention you/how hard they pushed?

Sorry if this question sounds stupid or uninformed but any insight into what generally goes on behind the scenes would be a big help. thanks!