95% sounds way high, but maybe I'm wrong. I think it's part generational - old school programmers are used to having to develop algorithms/etc from scratch, and the younger generation seem to have been taught in school to be more system integrators assembling solutions out of cut and paste code and relying on APIs to get stuff done (with limited capability to DIY if such an API does not exist).
But not all younger programmers can be Stack Overflow cut-n-pasters, because not all (and surely not 95%!) programming jobs are amenable to that approach. There are lots of jobs where people are developing novel solutions, interacting with proprietary or uncommon hardware and software, etc, where the solution does not exist on Stack Overflow (and by extension not in an LLM trained on Stack Overflow).
But not all younger programmers can be Stack Overflow cut-n-pasters, because not all (and surely not 95%!) programming jobs are amenable to that approach. There are lots of jobs where people are developing novel solutions, interacting with proprietary or uncommon hardware and software, etc, where the solution does not exist on Stack Overflow (and by extension not in an LLM trained on Stack Overflow).