This happens a lot in our feederish HS too. All of the kids being admitted to the most selective colleges are what I would call good students, but they are not necessarily among the best students in their class. Sometimes, but sometimes not. And sometimes they are recruited athletes, but definitely not always, or even most of the time. And I do think arts can be another way of standing out, and plenty of other stuff too.
But I am a little torn on all that sort of thing, because I have also seen it not work. Like, a kid is a great athlete in middle school, both they and their parents put a lot into that during high school, but then for whatever reason the kid isn’t recruited anywhere, or not anywhere they want to go. I think performing arts again can work kinda the same way, and other similar “year round” intense activities.
And of course I have no way of knowing for sure what that meant for their grades, college admissions, merit offers, and so on. But I have talked to quite a few kids or parents who think they did end up sacrificing some academics for their activity, and in their case they felt it didn’t pay off in terms of colleges or scholarships or so on.
So personally, I would not discourage someone from doing something like that, if they love it. But I would not necessarily encourage someone who did not love it. It might work out to benefit them for college purposes, but I think in many cases it does not.