I wasn't. A CMS can be used to build a real website.
But since we are presuming quite different things, that gets us back to the question, "what's a website builder?"
I was thinking more of the "no experience required, anybody can do it!", point, click, choose a layout, choose some cute animated icons stuff that some budget web hosts offer.
Unfortunately, IMO, "no experience required, anybody can do it!" is a fallacy.
Anyway, I think the poster is jumping the gun. Even professionals can't agree even on what a "website builder" is. I think that has to be settled before he worries about what a small business owner wants from one.
What's a website builder? :)