Most coding is pretty mechanical... and most juniors can pick that up easily. In spite of the mysticism surrounding software development, higher level languages are actually intended to be easy to pick up. If you have good problem solving skills, those are harder to replace with a couple of juniors (or ChatGPT).
If coding is mechanical, then the code will often turn out to be overheady, uninspired suboptimal solutions á la everything is a class, not well extensible and maintainable, or the task at hand truly not fit for the skill of a good developer.
Coding is a craft. There is an art aspect to it and there is a lot of room for inspiration and ideas to improve things.
I don't disagree, but in my opinion code organization (which is what most of these things are) is mostly subjective, in other words, beauty is in the eye of the beholder. Good organization certainly helps with maintainability and extensibility, but it's not a prerequisite, and it won't on its own solve tricky or vague problems.
Question: Wouldn't a couple of juniors be more expensive? I don't think I ever work at a company where junior developer was paid less than half of a senior developer.