Exactly, you have to know what to ask, especially on large codebase. I still have to baby sit Astra and opus 5.5 into reusing existing structures/functions, not reinventing the wheels, telling them "yes this might be a legit race condition, but you added 5000 LOC and I'm pretty sure it will never ever be a problem in production given it would require 5 distinct catastrophic failures at once to trigger it, if it ever happens log it in sentry and we'll have a look by then".
Some people are really really bad and won't even think about asking stuff like "run a memory profile and see if we can decrease our footprint", "benchmark the top 3 options for this bug and keep the one that uses the less cpu but still respond under 150ms".
You still need to have a broad understanding of what a computer is and how it works, both are skills, which a lot of dev didn't have anyways, but now they can shit out a looooot more code