The answer to this is nuanced. You can summon ~30k LoC codebases using CC without much fanfare. Will it work? Maybe, in some of the ways you were thinking -- it will be a simulacrum of the thing you had in your mind.
If something is not working, you need to know the precise language to direct CC (and _if you know this language_, you can use CC like a chisel). If you don't know this language, you're stuck -- but you'd also be stuck if you were writing the thing _by hand_.
In contrast to _writing the thing by hand_, you can ask CC to explain what's going on. What systems are involved here, is there a single source of truth, explain the pipeline to me ...
It's not black and white in the way I experienced this paragraph. The "details" you need to know vary across a broad spectrum, and excellent wizards can navigate throughout the spectrum, and know the meta-strategies to use CC (or whatever agentic system) to unstick themselves in the parts of the spectrum they don't know.
(lots of that latter skill set correlate with being a good programmer in the first place)
Many of my colleagues who haven't used CC as much seem to get stuck in a "one track" frame of mind about what it can and cannot do -- without realizing that they don't know the meta-strategies ... or that they're describing just one particular workflow. It's a programmable programming tool, don't put it into a box.