I don't know how you're assessing those pages, but bear in mind that
- Counting images can be misleading, since well-optimized sites use spritesheets or data URIs.
- If you're using something like Chrome's dev console to view requests, a lot of them are non-essential requests which are intentionally made after the page is functional.
- HTTP connection caps are per host. The benchmark is making hundreds of requests to one host, whereas a real page might make a dozen requests to the main server, a dozen to some CDN for static files, and a dozen to miscellaneous third parties.
- The benchmark is simulating an uncached experience; with a realistic blend of cached/uncached, HTTP 1 vs 2 performance would be much more comparable.
HTTP/2 is an improvement but if people expect a "5-15X" difference, they're in for a big disappointment.
The nytimes.com homepage makes 100+ requests to tiny images.
Same thing for the yahoo.com homepage.
An ebay.com listing page makes many requests to small thumbnails of items on sale.
And so on... This makes it a perfectly fair benchmark IMHO.