Debugging a problem is an attempt to understanding state behavior Fixing a bug are catering for a system state or edge case that was not envisioned before. It is thus not surprising the less you know about a system, the less you can predict its various states and behaviors.
Unit tests are pushed in an almost cultist way. Among the cult those that do not use unit tests are seen as knuckle dragging neanderthals or unenlightened. If you want increased stability you will need to first control complexity, to do that you need to reduce it. Unit test are thus band aids trying to work with complexity instead of reducing it.
Beauty is more important in computing than anywhere else in technology because software is so complicated. Beauty is the ultimate defense against complexity. (David Gelernter)