The alternative to providing APIs to detect features is to keep using the mess we're currently using. Previously, I would see you're using Chrome version X and

The alternative to providing APIs to detect features is to keep using the mess we're currently using. Previously, I would see you're using Chrome version X and know what features are available. All the APIs do is shift from using hacked together string.contains(...)/string.indexOf(...) calls (with bad lookup tables) to a proper format where I can just ask isXAvailable(). Basically, the same information is there, just in a more accessible way. And if you disable a feature in your browser's settings, isXAvailable() will now return false while UA checking says you still have it.