The expertise required of a profession is not quantified by the number of tools it requires, but by the difference in how much value an expert adds vs how much a noob adds. A noob designer will get you something that looks pretty to him or her. A good designer will get you something that gets users excited, tells them what to do, and how to do it, while being accessible to all users, while being extensible, maintainable, and within the constrained imposed by your site structure, CMS, and HTML/CSS/JS. This adds a lot more value than the noob designer, without needing any more tools, just being better at them (although, being familiar enough with your framework to know what's easy and what's hard is useful).

That said, I'm shocked that it seems to be difficult to find designers who also know HTML/CSS. Designers should definitely know how to use these tools as well.

That said, it's expected of developers that they continually learn new tools or improve their knowledge of existing ones. It seems however the same does not apply to designers.