If you only know how to style a page by applying pre-baked utility classes, you don't know CSS; you know a specific tool's API. The moment you enter an environment without that library, your ability to build custom layouts completely evaporates.
100%. That’s the ‘Platform Dependency’ trap. If you’re a ‘Tailwind developer’ or a ‘Bootstrap developer’ rather than a ‘Web Developer,’ you’ve limited your shelf life to the popularity of that specific tool. Learning the language specs—the ones that have been consistent for years—is the only way to future-proof your skill set.