Previous discussion about this by developers (170+ comments) who have been discussing Responsive Images in a W3C Community Group - http://www.w3.org/community/respimg/2012/05/11/respimg-propo...
I think there are other good reasons to prefer the srcset approach, but not this one. The email here provides motivation: <http://lists.w3.org/Archives/Public/public-whatwg-archive/20...;
Now, he decides that actually this is the way to go. Frustrating.
For reference, in the email linked above, Ian Hickson said:
> So why not just give the UA the characteristics and a template to use to build the file names itself? That way we still give the UA all the same information, but it is much less verbose and still solves all the same use cases. Thus:
<img src="face-600-200@1.jpeg" alt=""
src-template="face-%w-%h@%r.jpeg"
src-versions="600x200x1 600x200x2 200x200x1"></code>