Person surfing the web, clicks on link, ads blasted in face. (Just don't visit this random URL, nothing is forced on you!)

Person drives on road, billboards blast ads in face. (Just don't drive on this road, nothing is forced on you!)

Oh, and if you are going to argue that a website is not a public space like a road, then why the hell are you making it publicly accessible? Just lock that shit down behind a login if you are so private about it.