No, every change to a responsive site can break other resolutions/media queries without your knowing. Or do you routinely view your site on an iphone, Android, ipad, Kindle, netbook, laptop, and 30" monitor?
You're claiming responsive comes for free, or is no harder than purely non-responsive. Definitely not true.
You're claiming responsive comes for free, or is no harder than purely non-responsive. Definitely not true.