While Elena was busy with her side quest of destroying a criminal organisation and then was called to visit a new world, Eldriana and Dalia were done with their assignments too. They were doing extremely well and the speed in which they were growing was also extraordinary. Dalia was especially very close to reaching her goal of reaching level 300.
For that reason, to give her the last push, the next mission Elena assigned her was to kill opponents with higher levels than her own. This mission would definitely make her progression speed to be slower but it was best for her in the long run. For this last stretch, Elena wanted Dalia to earn high quality experience points. A person could get experience points by defeating both a weaker being or a stronger being. Was there no difference in those two types of experience ? There sure was.
