Right, but the client side did a query to see what was available and gracefully displayed a message. People are now sending the truthy response of the feature's availability back. You could be doing that as a legit bit of logging, or you could be doing that to be an asshat and deanonymize the user. The browser doesn't know the intent of being asked about a feature. And yes, it has been figured out just fine as a way for making someone money by selling information about you