I have only used Tailwind on personal projects, but I can't imagine it'd be harder than "regular" CSS, which is generally somewhat append-only anyway (you need a lot of team discipline to tame that somewhat).

In fact, I'd expect it to be more maintainable, exactly because it removes the indirection of CSS classes. They're an abstraction that don't make much sense if you're already using components, and the very point of that abstraction -being able to reuse styles- is the very reason it quickly becomes append-only. With Tailwind, you can safely delete styles, knowing it won't affect styles elsewhere in your project.