[dx034]

It's not. I know of several instances where IP is at least used as a filter. Esp. the combination of user agent and IP require no JS and can help you to track users across domains easily for small to medium sized websites.

[wglb]

Yes, if it is available it can be used.

The point of the assertion is that you can be tracked even if your IP address is obscured, mangled, or spindled.