I think they just haven't been bothered to change the advert
During the early days of AJX there were plenty of jobs elsewhere and they needed a decent carrot to attract people to the position. As time has moved on and slots have been filled the requirements have changed. In the past 1500 hours PIC on a CRJ would have got you the job. This then became 3000 PIC on something 737 sized and bigger and now they want a JCAB licence and prefer a 767 type rating. In theory they are still recruiting DECs but in practice the actual numbers through the door has reduced to almost nothing and certainly 'nothing' compared to 5 years ago.