Google's "Apps for Android" are not part of Android, but a propritary software suite. That the Chinese government banned Google services means companies making

Google's "Apps for Android" are not part of Android, but a propritary software suite. That the Chinese government banned Google services means companies making an android-based operating systems are not allowed to license Google's app suite. So in the final OS there is no way to add your Google account. The feature is not "disabled", it is simply not part of the software.