Because the managers screw up all the time and now they screwed up so bad that they dont have the capacity to train, they have to outsource training and go for DEC's.
It has been like this before you joined, is it fair? No.
You signed a pact with the Devil, thats a fact.
EK hired probably 100 FO's the last 3 month, guess what, in a year or less they will complain and be pissed off like you, like the guys before you and the guys before them.
History repeats itself