"absolutely NOT accurate" is intended in this case to mean that HTTP server logs do not accurately communicate the specific information (e.g. "Unique vistors and number of hits per day") that the presumably pointy-haired boss has asked advait to provide.
Your HTTP server doesn't serve every page view, as there are caching proxy servers out there on the internets. Your HTTP server doesn't know my Firefox browser with HTTP_USER_AGENT suppressed is a web browser with a human behind it -- it could just as easily be a bot and is likely to be categorized as such by most heuristic methods. Your HTTP server doesn't know if hits from the TOR network are initiated by one user or one hundred users. In short, your HTTP server knows only what is requested, how it is requested, when it is requested, and by which IP address. It doesn't know unique visitors, (human vision) page views, or any of that other stuff that makes marketdroids drool.
Thus, in context, my caveat stands.