Because there's a very crucial point...
Su Yuan suspects that Duo E has some connection with the Primordial Realm itself.
Otherwise, the strategy of Duo E hiding until the last moment when they need to continuously plunder the Cosmic Will to enhance their strength wouldn't make sense.
After all, people like us have killed Star Lords, even more than one, gathering a great deal of Cosmic Will, and have significantly advanced in Realm without the Emperor Level shackles.
Duo E, by merely hunting the former Universe Star Lord and collecting Cosmic Will, couldn't possibly catch up.
Moreover, according to Zhou Yun, when he killed Duo E, he had already obtained the Cosmic Will from Duo E.
This indicates that after entering the Primordial Realm, Duo E had other means to enhance their strength, not relying on these Cosmic Wills...
