I mean, screw performance. You can get away with a lot of shitty performance and still have a completely functional application. However, the kind of slop that happens around module boundaries that turns your codebase into a giant pile of workarounds and hacks really sucks.

And AI is particularly bad at this, as AI almost always prefers to work around a problem or do everything it can to meet the plan the user approved, even if that plan meets reality, it has problems. Which tends to lead to cascading misalignment with intentions and cascading infrastructure and architectural technical debt.

All of which culminate in less stable software, lower likelihood of long-term support of that software, and worse performance.