I remember same complaints about junior engineers copy pasting snippets of code from StackOverflow without understanding. And without curiosity to understand, without code review and mentorship from senior engineers they never grew to the senior level. But that is only some of them, others used StackOverflow to learn, did not use the snippets without understanding them first and properly adapting to their context, and they got good coaching in their teams and now have reached senior level from there. I see the same dynamic with LLMs, just more opportunities for both juniors to learn more by following up, and for seniors to to create tooling to enforce better architectur, test coverage and fault resiliency.
I think you're missing the point. Nobody removed people thanks to their SO copy-paste skills. If anything, more folks were hired to troubleshoot and sort out any copy pasta blunders (since you actually need working software, at the end of the day).
With LLMs this is no longer true - the thing can vibe a great deal before anyone notices that they have 100.000 lines of code doing what a focused, human reviewed and tested 10.000 lines can do. And as this goes on, it becomes increasingly more difficult for anyone to actually dig into and fix things in the 100.000 without the help of LLMs (thus adding even more slop on the pile).