a 14+ rating on a magical girl show isn't as much of a big deal as people think it is. there's obviously madoka magica, and even sailor moon got very depressing in the original manga. most original magical girl animes were heavily sanitised by 4kids-type dubs - cardcaptor sakura had a kid marry her teacher, ojamajo doremi had a kidnapping episode, and in sailor moon's last few volumes the protagonists die one at a time. idwtbamg's violence is unique because it's direct with real weapons, not because it exists in the first place.
The issue is, this is Japan's rating system (hence why these shows were watered down when they got here). This very specific age range is hard to find in the US and even harder to sell. You'll usually find ages 4-12 and adult and nothing in between. Animation studios don't know how to market to teens and find them to be a risky demographic to make stuff for. Infinity Train, Avatar, Jentry Chau and maaaaybe Owl House are the closest examples done here that I've seen try to lean towards that audience/even get greenlit.
I've seen MANY of my friends and colleagues pitch around hoping to cater to this demo but their pitches usually get axed in development because studios don't think it'll be successful.
Studios are incredibly metrics based nowadays and are still only looking at cable numbers or streams. And when you think about it that way, yeah it is risky to cater to teens because teens generally pirate the shows that they do watch (if they're not just watching youtube). Which isn't a bad thing but studios don't see that. They don't see that teens make up a HUGE majority of online fandoms because that alone doesn't make them money. It COULD but that would require doing merch and learning how to pivot into engaging with online spaces which is, again, too risky for them. They can't replicate the success of studios like GLITCH or Spindlehorse, who have hit that teen demo PERFECTLY, because if they do try, it'd require them to dismantle the VERY OLD system and reassess EVERYTHING.
