Not quite, but new and unproven features are supposed to be hidden behind a runtime flag to prevent a hot mess like what was caused with CSS/JS vendor prefixes.

The Blink team are getting better at this, but they still really need to put their feet on the brakes a little more, and wait until there are at least two implementations ready before flipping their own switch to enable the feature for all of their users.

With two reasonably complete (and independent) implementations it's far more likely that the standard is engine-neutral, and not lacking in crucial detail. The web platform tests will also have been put to the tests to ensure that they have decent coverage. On top of that, the feature can be considered to have been vetted to ensure that it isn't really just being shoved on the web to meet Google's business needs, but rather in the interests of a broader set of people. These things can easily slip if pushed too quickly, even if others are generally supportive of the general idea of the feature.