User blog comment:Crimson and Darkness/DxD Updates 2~/@comment-25072311-20170823085817/@comment-2601:8C:601:5692:1977:AFE0:EC4A:85A3-20170901014923

Technically, EX didn't exactly make BorN (Season 3) non-canon. It offered up the possible existence of alternate (parallel) universes that diverge from the events of the "main" universe of the novels. Thus BorN was "explained" to be one of those many possible universes that may or may not exist. Honestly, the whole point of EX (other than allowing us to meet a possible version of Issei's children) was to placate fans of the novels. As far as those who only watched the anime, would they even care?