Correct me if I'm wrong, I've heard that ATHR OFF at easyjet is forbidden,
You're wrong. It's not forbidden - but it's unusual to see on the line.
And given the architecture of the airbus thrust lever quadrant, it's understandable. In the Boeing, for instance, the full arc of motion is available for manual thrust, so setting a particular thrust is relatively easy. In the airbus, the top third of the thrust lever arc is used for the Autothust setting detents - TOGA, FLEX/MCT and CLIMB - and the bottom third is used for reverse thrust (unlike the Boeing, there's no piggyback lever), so that just leaves the centre third for setting manual thrust which makes manual thrust lever movements "three" times more sensitive than in the Boeing.