What prevents HTML pages from using progressive rendering?

Question

I noticed that some pages begin to render almost immediately, while others sometimes have to wait until many or all of the resources have been loaded (javascript, image, css). In the worst case, it seems to be for a large page, on a slow connection or server. One particular page I'm looking at reaches nearly 2 MB, with 30 different .js files, a dozen .css files, and 80 images.

I know about the offers of http://developer.yahoo.com/performance/rules.html , but what prevents the browser from trying to display the page before the last item was loaded?

Answer 1

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Answer 2

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