Every selector has the potential to have unintended side effects by targeting unwanted elements or clashing with other selectors. More surprisingly, our selectors may even lose out in the global specificity war, ultimately having little or no effect on the page at all. Any time we make a change to a CSS file, we need to carefully consider the global environment in which our styles will sit. No other front end technology requires so much discipline just to keep the code at a minimum level of maintainability.
Many years ago, I worked for my parents who own a video production company. Because it is a family business, you inevitably end up wearing many hats and being the czar of many different jobs. I mainly managed projects and worked as a video editor. On production, there were times that I was called on to work as an audio tech and was made to wear headphones on long production days. In those days, having a really good set of headphones that picked up every nuance of sound was essential to making sure the client got what they needed.