As a developer, I can foresee websites using features other than navigator.userAgent to detect Chrome, because it’s easy to change its value. For example: for now, navigator.getBattery is available only in Chromium, and it doesn’t need permissions to be checked for its existence through typeof navigator.getBattery === 'function' (also, the function seems to be perfectly callable without user intervention, enabling additional means of fingerprinting). While it’s easy to spoof userAgent, it’s not as easy to “mock” unsupported APIs such as navigator.getBattery through Firefox.