[menor]

Using a nice component based architecture and Sass you can also achieve the same, for me is more maintainable changing a key value in a map and having a new type of button generated than having to copy/paste the rules. And I think learning Sass is not that difficult if you already know css.

Not having lots of nested divs with lots of class names also helps to code readability and maintainability if you use something like React with JSX.

I see advantages in not needing to precompile in the future, but apart from that I see this as a step back, of course it's my opinion, I see how this can work for other people.