Why did Maori musical traditions treat polyphony as a performance fault?

In Maori musical tradition, polyphony is considered a performance fault because the music is structured around narrow melodic lines that undulate around a central tone, known as oro.1

Because the aesthetic requirements of these performances demand that the music remain uninterrupted—even by the singer's need to breathe—the tradition relies on multiple singers staggering their breaths at different moments to maintain a continuous flow. Consequently, the introduction of polyphony would disrupt this specific melodic and rhythmic continuity, leading it to be classified as a technical error in performance.1