Earlier quoted context omitted.
> because I only write it once, in my Button component. Unless of course you have several similar buttons with only minor differences between them. Maybe copy-paste? And then you have to slightly tweak your buttons... Or add conditional effects or dark mode and the complexity explodes, just on a simple button.
The same is true of CSS classes, though - there you have the same choice between reuse and duplication. Do you have .button-primary, .button-secondary, etc, or do you use modifiers instead? The combinatorial complexity is inherent in the design of these sorts of components, you won't get away from it just by using a different tool to write your styles.
You separate it into a .button class, and then further specialize it by adding more classes (like ".button .button-primary").
With Tailwind everything is duplicated, but with CSS you can move out the common parts.