..." 'episkopos' (overseer, guardian), 'presbyteros' (elder) and 'diakonos'(servant) for the first two centuries".....

Maybe for the first two centuries the Christian Church followed the thinking in the Epistle to the Hebrews, and avoided trying to have any 'priest' other than Jesus, our 'Great High Priest" who made any other 'priests' unnecessary. 

But afterwards the thinking and attitudes of needing a 'priest' to represent the rest of us seems to have crept back in. Whatever they did in the first two centuries no longer applies. Monica seems to be speaking of our current 'reality'.