I agree. You can also use Tailwind in CSS modules or in SASS, or create your own CSS helper classes. There are many tools available that merge and allow conditional CSS classes. Basically, you can use the same tools as in vanilla CSS to organize your code.
If you use any component library, most of your CSS should be within the component library, not in your application. Components can have variants, such as primary and secondary buttons, for example. This adheres to the DRY principle. Your application can also have reusable components, which helps minimize the use of CSS and HTML. This adheres also to DRY. You can also build your own Component-Library.
You can apply the same programming principles and organizational patterns to HTML and CSS as you would to any other code. This becomes much easier if you separate the view from the rest of the application.
If you use any component library, most of your CSS should be within the component library, not in your application. Components can have variants, such as primary and secondary buttons, for example. This adheres to the DRY principle. Your application can also have reusable components, which helps minimize the use of CSS and HTML. This adheres also to DRY. You can also build your own Component-Library.
You can apply the same programming principles and organizational patterns to HTML and CSS as you would to any other code. This becomes much easier if you separate the view from the rest of the application.