Easy:
Just Dance Now[0] is not a AAA game. It was made by Massive Entertainment, who makes AAA games.
So, a game being produced by a AAA studio does not make it a AAA game.
What "is" and "is not" AAA is debatable, sure, but some things are clear:
1) they're not mobile games.
2) They have a lot of marketing budget
3) They generally push the limits of the platform (lots of LOD)
4) They have large development teams
AAA usually means that a game needs: Lots of time, Lots of Money and Lots of People.
Fortnite is low fidelity, has been in early access since it's inception (many years at this point) and has a relatively small number of people (<100 direct, compared to >1,400 for The Division) making it, even though it's been "in development" for many years, not AAA level.
FWIW I'm not saying AAA is "good", I'm just saying that Apple isn't chasing AAA- and "fortnite" is not a good counter-argument, the better argument might be call of duty or sims, which have mac ports, but they're definitely not first platform and they actually are emulation shims using Wine.
Fortnite itself does not claim to be AAA, and it's totally fine not being AAA, it's actually better to avoid making AAA games and instead go for "AA" with low fidelity because the stakes are lower and you can take more risks in making a more interesting and engaging game.
[0]: https://en.wikipedia.org/wiki/Just_Dance_Now