Yeah, but japan has... Unique relationship with smut, to say the least. Many of their mainstream manga and anime are already borderline nsfw as is, so it's not hard to imagine actual porn artists finding work in "family friendly" areas.
Also, the Overwatch example another curiosity and probably an exception, as so far as I heard there's a rumor that prior to the release of the game they outright weaponised R34 for promotion by covertly commissioning a whole crowd of NSFW artists to draw pictures with the characters of the game, because one moment there's virtually no Overwatch fanart and the next second we're drowning in a particular kind of it.
