Judging by parent's CV, it kind of looks like they are relatively new to the industry and working in areas where they are heavy on the greenfield side of the equation. I get the sense that they've probably had some good success on smallish projects where they are in charge of keeping it all in their head. That's not to say that isn't earned or otherwise valuable experience, but it surely is not the way a lot of software projects are situated. Parent: I hope you won't take my comment here as a slight. I mean no offense, just pointing out what I think is probably valuable context.
Yes - this is certainly true. I would have to concede that I could not speak to how my thesis would map onto a truly colossal codebase.
That said - I would (again, maybe naively) suppose it's not hugely different - much of the work I do occurs in code where many people have and will work on it, and where the size of the codebase dwarfs model context windows.
In that case, I feel the same - current frontier models, when properly oriented to a task, with some assist on the big-picture thinking - are more than capable of generating good code that can slot into big codebases with many moving pieces. Of course, I'd have to point to other people's work to defend this, but I think that's still pretty reasonable especially against the declared "LLMs are worse than useless for generating code".