I wouldn't be on this board if I didn't think it was a mystery.
That said you don't want every debate to come down to two fixed camps, those supporting alternative (but un-provable) theories and those de-bunking them.
So however improbable it seems, convention COULD be right if there were collosal organised human resources, (I cannot see any other way unless tools, timeframe and accepted technologies available to the AE's are wrong) , now of course if the population level makes that a non starter then you can get an accord between the two camps.
So given the rate at which blocks need to be quarried, moved and placed, the timeframe it was done in, injuries, support staff etc what's the best estimate for manpower required ?
Given that this wasn't the only thing the AE's were doing/building/fighting what would the population need to be to make this practicable ?