In addition to meeritas point about pseudo classes and media queries, I'd add that the fact that it narrows down the space is an important factor. The classes mean that I need to find the best fit rather than spend hours matching pixels by hand. It's like going from drawing charts on blank paper to grid paper. You stay within certain boundaries. It seems like a detail but I find that in practice (and in fairness, I've only been using Tailwind a bit so far), this makes a significant difference to the way I think and work with UI.