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ASUS is apparently killing the ability to root present and future Zenfone, Updated
(www.androidauthority.com)
This is a most excellent place for technology news and articles.
Which means, legally, you can no longer own even the hardware of a Zenfone you bought, you now only license it. Since their OEM software is proprietary and in nearly every software's TOS they can revoke your license to it at any time for any reason, which would effectively brick the phone if bootloader unlocking is not possible.