IDK what calvin had in mind, but the client pull model you suggest can require a lot of round trips. Request a, parse a, execute a, request b, parse b, execute b, request c, parse c, execute c.

Of course, you could always do server push, but hey...that's pretty close to what a single bundled file is :)

I don't have a specific link/reference I can provide you, but it came out during Q&A at one of the HTTP/2 presentations at Velocity Conference 2016.