Lmfao case in point! "Flashing the rom again restored root access" NO IT DIDN'T! How can you flash a rom on an unrooted phone...?! Lol thanks for that, updating the guide as it's evidently not perfect for all situations
You don't necessarily need root, with an unlocked bootloader you can flash a custom recovery and thus a custom rom without having root access (except through the recovery which was loaded with fastboot).