By all intents and purposes, the Persona games (3, 4, & 5) look and play like Rated T games for teenagers. Despite the Rated M labels on their boxes, none of their content really screams out "only for Adults". No overt examples of gore or sex scenes to take note of. You know. Stuff that typically launches a game into Rated M territory. Honestly, their overall aesthetic and target audience seems more geared towards teens than adults.
And then it got me thinking. What if devs started making more games like that? They could just make games without giving a damn on whether it gets a certain age rating or not. When devs go for a Rated E rating, they self-censor their game's content to be suitable for kids. When devs go for a Rated T rating, again, they self-censor their games and remove any adult material too risque for teens. Leading devs to dumbing down their stories/dialogue to fit a certain demographic, whereas an Rated M rating could've given them more freedom to approach such topics that neither an Rated E or T rating would've allow.
The thing that Persona devs seem to do is to "attempt" to create a Teen-looking game, but they don't really give a shit what rating they're gonna get in the end. As such, their teenaged characters feel more like realistic teens as a result. Especially when they're grappling with adult subject matters like murder, alcoholic dads, or getting raped at school. Or cursing like a sailor when they get angry. Like take the villains in Kingdom Hearts for example. They never curse at you. They just lamely threaten to extinguish your "light" with their "darkness", because the writers have to pull punches in regards to using any "adult" insults. Now take a look at the villain in Persona 4. The dude just straight up calls women "worthless bitches" and one of the protags keeps calling him an "asshole" or "bastard". That's much more believable writing imo than Any Rated T game.
Before devs today became so focused on getting a certain rating, there were often villains in old games that crossed the line many times. Final Fantasy 6, a game that looks kid friendly on the surface, even had a villain that poisoned a child to death and you see how the father reacts in grief. It moments like those that you don't see in Rated E games anymore.
The reason why you, an adult, find the dialogue/content in modern Rated E & T games as childish is because the writers have to dumb it down to fit a certain rating. I'm just arguing that if a dev sends their game to be reviewed by rating board, they should just accept whatever rating they get. If they were hoping to get T rating but the board gives it an M rating, they shouldn't have to go back and censor the content to fit a T. The dialogue and/or cut content usually suffer from such self-censorship.