Writing CSS that scales is hard, even when you're great at it. It often starts well, but soon, unforeseen requests start coming in, the layout is being moved around, and you have to undo most of what you've done. Soon, you realize that your component-based architecture isn't as resilient as you thought, and it feels like the best thing you can do is to start over.
There's one methodology made for change. Instead of being tied to your project, it's tied to your style guide. This is called utility-first CSS.