When Karl Marx first introduced the idea of Communism it was very similar to this "anarchist communism" that you have mentioned.
The reasons that dictoral communism cannot work are.
1. Human greed.
2. No single person could ever create or manage an eutopia because there is no such thing as a "perfect being."
A good example of a failed dictoral communist government is shown in George Orwell's 1984.
And so we ignore the beggar's cup
Praise your act in the Grand Finale
Teach the unborn the winners sign
a welcome grin to the world Royal