The call for CSS specialization strikes me as seriously misguided (even before agentic coding became a thing). Yes, web development is complex and you can’t know everything, but it is possible to learn what you need as you go and generally build up a strong high-level sense of what is possible and what approaches are reasonable for quality. But web development is not rocket science. Someone with CSS skills but not JS…
I'd always been amazed over the years by how many people didn't even attempt CSS. They looked at it like an after thought. Reminds me of a favorite Archer quote: "I thought we skipped that step.", "Skipped a step... in bomb defusal...?"