> For example, in a scriptless world, your HN up/down vote can't be done without a full page load, which would come with the added headache of changing the state of the world on your page because stories and comments have changed their ordering. Solution? Return of the chronological thread (no thanks).

I don't see why it would have to change the state of the world on your page. Sites like HN in a scriptless client world would still be programmatically generated on the server, and presumably could still keep track of state via cookies or via adding parameters to links when they generate the page.

Up/down vote could reload the same view you had before voting, with only the effects of your vote added.