Not just that, I remember learning all of the different systems and being told how invaluable it was for research.

I caught what must have been the last itty bitty tail of that. I was a 3rd grader in 1993 and were taught all about the card catalog and the Dewey decimal system and taking notes on note cards and organizing them in notecard boxes and how important it all was for research. I'm glad we moved on from that. For me, it was a drag.

IIRC from when I visited a library earlier this year, they were still being used in the genealogy section.

Yes, I remember them but also observe that we’ve moved on from those trays of cards in narrow drawers systems (and good riddance!).

Those cards are no replacement for literal grep, of course. They were a search across a tiny summary of the contents, albeit a fairly structured one (which is helpful for some searches).