> The way Google released "experimental" features behind prefixes instead of configuration for years always seemed like a way to get developers to break their sites in non-Chrome browsers as much or more than a way to test features.

Apple, Mozilla, Microsoft, and Opera all were doing that before Google even had a browser; there never even was a Chrome-specific prefix, all of the features included in Chrome this way were -webkit- prefix and, IIRC, implemented in the WebKit shared codebase.