[bostik]

> And there's the risk of the 'not so competent programmer', who knows how to fix stuff, without thinking far enough.

I would actually claim that majority of non-seasoned programmers fall into this category.

It's rare to see an engineer who would actively set out to destroy or cripple the system they are working on - but it is incredibly common to see one fix the problem they have at hand, using what happens to be available, and make the overall system just a tiny bit less pleasant to work with. Or understand. Let alone maintain.

Repeat the above a hundred times and your codebase would make Lovecraft take note. If each such modification reduces the quality just 0.5%, after 100 rounds you're looking at an aggregate damage of 40%.