Wouldn't they have to, to support browsers without pushState? And even if they used terrible JavaScript hackery to get around that (serve same content for every URL, have clients AJAX in content based on location.href) how would they support web crawlers? I thought the whole point of the hashbang was that you would get the original content (or an equivalent representation) by removing it from the URL, so I'd think they still support backend rendering at some level.