In the past when they've spoken about why they delayed implementation it was often due to security issues (e.g. Webgl) or due to the standards proposal not bein

In the past when they've spoken about why they delayed implementation it was often due to security issues (e.g. Webgl) or due to the standards proposal not being mature enough and them being worried that supporting it would lock in a bad version of the spec because people would build code on top.