Whole-tone scales and polytonality are foreign to music of the classical era. However, these became common for early 20th-century composers like Claude Debussy and Igor Stravinsky, who were searching for a new musical language. In this later context, these were legitimate new techniques in serious music. In Mozart's time, however, these non-classical elements gave the piece its comedy, expressing the composer's humor."
I have said in the past. The summary of 20th century music is composers taking bad compositional technique and then take it to the extreme which lead to people subsequently call it genius.
It's a century that celebrates bad technique of composing
If a little bit of polytonalitt sucks why does creating an entire compositional technique regarding polytonality is suddenly genius
If writing a little bit of a disjointed music due to poor usage of motivic development is bad. Then why does writing an entire composition with a complete absense of motivic development is suddenly genius
If writing music that sounds out of tune is an example of bad composition technique why does creating an entire compositional method (called 12 tone technique) where there is no sense of "in tune" is suddenly genius
It's this stupid notion that artistic intentions matter in judging the work of art. If the artist intends to write music that sounds out of tune via a sophisticated technique it is considered good while a composer who intended to write a tonal piece of music but due to incompetence sounds out of tune it is bad. However from the listeners point of view they are indisguishable and should have zero impact. If anything the former is far more obnoxious, a person attacking you and deliberately injures a person is far more culpable than someone accidentally injuring a person due to negligence and incompetence