Recently passed a training course at Dogfish Head that started us on a path of being better tasters of beer. Beer is the sum of a few parts with intricate processes mixed in to help it along. A website is similar in that there are disparate parts that when combined create a new thing.
One of the core components to beer is the hop, if you let it sit around it can start to stink of bad cheese and that off-flavor is called Isovaleric. This single thing can ruin a beer thats made up of many other ingredients and chained together processes.
Similarly, CSS is a core component of a web page and over time can begin to stink of outdated unused classes that bloat your page load times. Just like a stinky hop this bloated file could weigh down a page that needs to be loaded fast.
Brewers and developers must focus on and sweat the details in order to create an end product that meets and exceeds expectations. Whether it is hop quality, a well structured DOM, performant javascript, or boiling temperature a simple mis-step can ruin ruin a beer or page render.