The problem is that there's an impetus to continue working on top of established facilities, because it's usually incrementally less work than reworking a piece

The problem is that there's an impetus to continue working on top of established facilities, because it's usually incrementally less work than reworking a piece of code into something else. Plus it's difficult to recognize ahead of time when something is about to become a problem, rather than fix something that's already a problem.