Nintendo is expert into jumping in the trend late and still making masterpieces with those. Splatoon arrived when console FPS was no longer hyped, BotW arrived when open world games were fading, and so on.
Because of said "cute"-ness factor, the parents who are aren't fully aware of what the idea stems from or other, similar reasons, are willing to let their children play this game and the seeds of a more competitive edge on what is otherwise roughly a ~90% IP. To be honest? It's clever long-term.
Now, you take a beloved franchise and you get as many of the hardcore fans involved that grew up with the series, plus the general exposure to newly-created fans, and then market it at the angle of younger children because it's a "cute" way of expressing MOBA tactics. /2
Most MOBA games I've seen are either too gritty/bloody/sexy for "concerned parents" who don't have any clue what games are like because they do not care to educate themselves on the matter or are just overly sensitive helicopter parents who really need to take a goddamn chill pill. /1
