User blog comment:Crimson and Darkness/Shin DxD 3 discussion/@comment-82.160.23.173-20191223201551/@comment-26926813-20200128135401

Well its just simple logic. If ExE is Eros Engine when it would be very poor upgrade as every single other Ise forms every time were something great but to next form become just method for better control (longer use of Ryuteimaru as Eros Engine its power sourse in first place) Ryuteimaru? Its not something great.

And Ise already reach Abyss side according to Vol.21 Life. Lucifer