It's internally inconsistent, so you can't guess what the Tailwind class name is for styling, while you can do this for CSS on the majority of properties. In Tailwind, font weights are just `font-bold` for `font-weight:bold`, while font variants drop the `font-` prefix part, and become `ordinal` instead of `font-variant-numeric:ordinal`. That's not an isolated example, it does the same with text-color versus text-decoration, and text-decoration-color adheres to neither of those systems.
It's quite close to learning an entire new styling language on top of CSS. It may be the case that putting everything into the HTML is more efficient from a productivity point of view, but I don't think Tailwind's specific implementation achieves that.