User blog comment:B214/Shin DxD 1 discussion/@comment-30230931-20180804194539/@comment-28884330-20180806160614

Skills as a leader and king are negligible when Issei surpasses her in everything else, all vital aspects. And when Indra said Rias has become strong without him he refers to things such as her quality as a King, the team she amassed and the Balor form she acquired. All of these except for quality as a King have been surpassed by Issei.