"If your content is really interesting, then there is little you can ultimately do to protect it"
That's true, but most copying, in my experience, has nothing to do with "ultimately" or geeks or determined plagiarists or anything like that. It's usually casual copying by clueless people, and even a simple, easily defeated protection (easily defeated by folks like us, that is) works quite well to stop them. They don't know anything about "view source" or caches or anything else... heck, they don't even know what a web browser is or that they're using one.