You (as a developer) could scroll by 1px to remove the address bar in iOS6. It was useful to give your page it's own top navigation or just have more content visible. That was not possible in iOS7.
So you want to fill the user's limited screen real estate with your own useless crap (usually "download our app and subscribe to our emails!"), and you're worried that the actual functional bits of the browser are getting in the way of your doing that?
because for interacting with web apps those default browser buttons are just as 'dangerous' as ads for the user accidentally tapping them and navigating away from the page
