Yes, better graphics doesn't always implies being more explicit, but sometimes it does. Look at Doom, GTA or Metal Gear, they evolved from their primitive origins and added explicit violence or nudity.
I can't speak for Metal Gear but Doom and GTA both had mature content in them. Aurora's claim is that visual fidelity, not game's content, dictates age rating, which is just factually not true.
GTA 1 and 2 do not have any mention or appearance of sex. Metal Gear had no nudity until MGS2 (and come dangerously close with Quiet in MGS5 with the "she breathe through her skin" excuse). Doom is debatable but I'll argue that the added gore between Doom 1 and Doom 2016 is separated by such a giant leap that is qualifies. I would add The Last of Us to this list. The first episode only had some passing mentions, the second has very graphic and upsetting content.
