To speak more directly - every codebase has local reasoning and global reasoning. When looking at a single piece of code that's well-isolated, you can fully understand its behavior "locally" without knowing anything about any other part of the code. But when a piece of code is tightly coupled to many other parts of the codebase, you have to reason globally - you have to understand the whole system to even understand what that one piece of code is doing, because it has tendrils touching the whole system. That's typically what we call spaghetti code.

If you leave an AI to its own devices, it will happily "punch holes", and create shortcuts, through your architecture to implement a specific feature, not caring about what that does to the comprehensibility of the system.

There are software that works like this (e.g. a website's unrelated pages and their logic), but in general composing simple functions can result in vastly non-proportional complexity. (The usual example is having a simple loop, and a simple conditional, where you can easily encode Goldbach or Collatz)

E.g. you write a runtime with a garbage collector and a JIT compiler. What is your map? You can't really zoom in on the district for the GC, because on every other street there you have a portal opening to another street on the JIT district, which have portals to the ISS where you don't even have gravity.

And if you think this might be a contrived example and not everyone is writing JIT-ted runtimes, something like a banking app with special logging requirements (cross cutting concerns) sits somewhere between these two extremes.