The Switch plays host to all sorts of games. There are thousands of titles that span tons of genres, and those games fall into all different ratings categories. There's a fair share of Mature-rated games on Switch, and Nintendo has no problem with those titles finding their audiences. Apparently someone at Warner Bros. wasn't aware of this.
Scott Hawkins, head of the developer relations team at Nintendo of America, shared quite an interesting story during his BIG Digital 2020 presentation. Hawkins noted that an exec at Warner Bros. thought Mortal Kombat 11 wouldn't fit with Nintendo's friendly image, and therefore wouldn't want the game on their platform.
“When Warner Bros. got the first playable build of Mortal Kombat 11 up and running on Nintendo Switch, I flew down and met with the team down in southern California. One of the executives there was meeting with me and showing me the game, and we were playing it, and he looks at me and he says, ‘Scott, are you sure Nintendo wants this game on Nintendo Switch?’ And I said, ‘Yes, we absolutely want this game.’
He was concerned because it’s a mature-rated title that it wouldn’t be Nintendo-friendly. But clearly after seeing the first month’s worth of sales and see it be the number one game on the platform, it shows that yes, there is an audience. There’s an audience for lots of different types of content on the platform, and this was a big success.”
Back during the SNES era, Nintendo did indeed take issue with games that were too violent, included foul language, showcased religious iconography, and so on. Obviously Nintendo's approach shifted leading out of the SNES era and into the N64 era. Still though, Nintendo's desire to make games for all ages, along with how they used to operate, still sits in the minds of some people out there.