[Brian_K_White]

I would say that knowing that there are such things as different families of regex compiler, what their internal methodologies and consequences are, so that you can avoid certain otherwise non-obvious problems that arise not from something you did wrong, but something a layer lower did wrong (you wrote a valid regex according to all the rules in the manual, and got a bad result) qualifies exactly as an example of needing to have some understanding of how the layers below work.

In fact it wasn't necessary for me to qualify that with "I would say". I do say, and it simply does. You've made exactly no argument this entire thread.

Maybe everyone doesn't need to know everything, but the skin of stuff anyone needs to know is thicker than 0, and has no absolute boundary layer either, you just generally need to know less the further from your own work. But that never goes all the way to 0. You have to rely on other people to have done their jobs, but you still at least have to understand what those jobs are, that they exist and how you ultimately interact with them and how they impact you.

You said so yourself several times which makes this all farcical.