I'm aware of the distinction. However, part of the goal of SPDY is to avoid round-trip by pre-emptively sending resources. So the question still remains, why

I'm aware of the distinction. However, part of the goal of SPDY is to avoid round-trip by pre-emptively sending resources. So the question still remains, why not use some type of archive format to send the HTML along with the images and other assets that would have been pushed down the pipeline? Clients could negotiate for the bundle using Content-accept, and proxies would not be broken.