Utility-classes like `font-16 font-bold font-purple` are essentially just shorthand for writing inline CSS. You are defining the styling in HTML, with a utility CSS file as go-between, true, but if you use Tachyons or Tailwind the way they’re supposed to be used, the way to change the look of an element is to go edit the HTML.

For component libraries, that makes a lot of sense. You re-use snippets of HTML that is styled a certain way. No need to set up another re-use layer using CSS.

I expect the next level of utility-first CSS will do away with the CSS file altogether, and start baking the resulting styles directly into the HTML, so <div tx(['font-bold', 'font-16', 'font-purple'])> would be transformed by whatever you use for HTML rendering into <div style="font-weight: bold;font-size: 16px;color: purple">. That would complete the circle and cut away a lot of complexity.