They are (encapsulated in reusable components). But when the project grows big, Tailwind's shortcomings become apparent, the biggest ones being the loss of context (cascading) – and of course the lack of separation of concerns, when the concerned parties are also separate (developers and designers).

When building a design system, there are a bunch of default styles, and then there are variations based on context. To put it in a real world example, imagine a newspaper heading style that varies depending on where the heading appears. Front page headings are bigger, sports pages might use a different style, and so on. Same with buttons, cards, tabs, what have you.

This isn't impossible to build with Tailwind by adding, say, react logic, but it becomes a mess quickly. If you have a well-built design system, class naming shouldn't be that hard to figure out and communicate to developers. But deciding on a coding logic to account for these context changes and sticking to it seems not as easy, especially when developers come and go.