if you are in a big project and want to refactor classes the string concatenation pattern gets extremely painful, it’s even worse when it’s done on the server and on the frontend. At some point you will have trouble removing your classes. My company did this a lot and know we struggle to clean it up since basically all classes are used somewhere. What we do is basically use purgecss and than diff it and look for all occurrences that got removed which will take us a few months.