But from an interoperability aspect (relying on implementations) the market didn't think it was better or we'd be using it still. HTML5 won because it was simple and met many needs demanded by the market.
The simple standards that provide more benefits, but most importantly are highly focused on interoperability and simplicity, win, always, even if they seem subpar from an exactness standpoint.
At one point in time SOAP had the same religious hype surrounding it that HTTP/2 seems to have. But sometimes you have to take a step to realize you are slightly off path according to the market, not what you might want to design and what should win but what happens with interoperability in the market. HTTP/2 and XHTML type standards are steps, to something better but are too top down or ivory tower eventhough they have lots of awesome and needed features.
Note that I don't especially like HTTP/2 and believe that a hack like SPDY should not make it to a standard. More time and care should be made to make a central protocol like HTTP (central in that it is used alot).
[0] Source: http://www.techrepublic.com/blog/10-things/10-things-you-sho...
>Instead, the HTML5 spec is written so that you can write HTML5 with strict XML syntax and it will work
And it couldn't have been XML, because HTML predates it.