These days, with retina screens, that's a good policy, as far as I can see. There is a lot of work being done at the moment to devise an HTML solution for dealing with responsive/retina images, such as the <picture> element, but it's a hot debate with no obvious resolution (hehe) in view yet.
The technique I described and linked to seems to work really well in my experience, except for images that contain text. It doesn't seem to work too well for those ... though I'd question why text is in the image anyway. If it's a picture of a sign, then fair enough, but for a banner or similar, the text should be real text anyway.