If you cannot prevent something, you might as well be a part of it. Unofficially.
Sorry but without Apple a technology like this would go nowhere. Half the mobile traffic on the web comes from iOS and is significant enough on Desktop. And is there something Apple has done with WebKit to deliberately prevent a technology from being adopted ? They supported WebGL for example.
This technology is backwards compatible (at least at first), so a particular vendor's support is not needed, in the short term.