I came into the US tech industry in 2011 from a CS program (programming on my own longer), which was basically a pipeline into Java or web dev at that time (the classes on other things like OS, compilers, and FPGA were a thing, but seen by most as a hurdle not a promising or practical career pathways).

Most of the people I dealt with for the decade following that (i.e. pre-LLM) had little clue how any part of computers worked, and I don't intend that to be particularly pejorative, it's just that it's been somewhat easy to carve out a niche doing something to do with programming while having little understanding of the small or big picture.. all heuristics and applying working patterns.. for a few decades.

You can still understand whatever you want, today, with added tools. It's just a choice to turn your brain on or off. I think LLMs are perfectly fine as a learning tool to interrogate a subject, do comparatives, and then formalize your understanding by reading the sources. At a macro level brain rot is real, but it cuts across all generations and it started long before LLMs.