Sure they can, there is nothing stopping other developers from adopting more cartoonish art styles for their games. Borderlands and Sunset Overdrive both come to mind. Using a certain art style doesn't determine the genre for a game, any game can be portrayed with any art style the developer so chooses.
Visuals don't define the genre, but
do define the game. Take Mario Galaxies and slap onto that gameplay a gritty space-marines look. Is it the same game with the same appeal? Of course not. Nor would God of War be the same game with cutesy bobble-headed characters and confetti-blood, any more so than...Saving Private Ryan would be the same film if an animation with cuddly animals.
The right look is essential to the overall feel of a product, which is why lots of money is spent on employing people to do the right job, and lots of time is spent learning how to match up visual and audio aesthetics with a product or service. Gran Turismo
needs photorealistic rendering to be GT, otherwise it'd be a different racing game.
The rawest example of this is to replace all the final art with the developer art. A game loses almost all meaning when the avatars and visual cues are replaced with flat squares, spheres and capsules. Take a horror game like Aliens:isolation or P.T. or ZombiU. Replace the moody lighting with flat-shaded polygons, remove the eerie soundtrack, and replace the heavy breathing and footstep sounds with debug bleep and boop placeholders. Suddenly it's not at all scary. Place in some artwork, some concept art sprites in place of the alien, say, and it's still not scary. All the pieces have to come together and fit just right to get the correct emotional response from the players.
As such, a limited palate of visual styles limits the scope of experiences. Nintendo are happy to limit themselves to that scope, but it won't do for every developer to go that route. ZombiU is 30 fps to enable the essential moody visuals.