I mean, yes and no. It's a martial arts system in the sense that it incorporates combative mechanics, and I do know of people who attempt to incorporate it into combat against resisting opponents, but some people take issue w/ calling it a martial art because of quack "masters" claiming to be invincible (but then getting their ass kicked within seconds by some MMA dude), and also partly because the popular calisthenic variety is not combat-oriented.

IMHO the biggest dissonance between western idea of "intense" vs eastern is that westerners think of intensity as optimizing for burst amplitude (in martial arts' case, specifically honing combative prowess), whereas easterners think of it as a matter of consistent holistic development (core strength, balance, attention, etc).