Dunno about "expert", but I teach this stuff regularly and EoD is quite right, it's used to derive the QFE when only the QNH is available. Some operators still use QFE, and some types require one altimeter to be set to Threshold Zero for take off performance reasons.
A common source of confusion in your situation of 0 hPa, is when do you follow the QNH Altitudes on the Approach profile, and when do you use the QFE Heights, when you haven't changed the actual altimeter setting?