In case there would still be some people around, who are burdened with an increasing doubt whether 'modern music' in the last century was indeed as insane as it seemed, taken seriously by many establishment spokesmen/women, then here there is some evidence which would quench such doubt:
It is no coincidence that such undertaking followed in the wake of a political unheavel of unrivalled proportions and with a future of millions of crimes against humanity. For people, imune to reason, insanity is infectuous.
The term 'genius' is often appropriated to mask the most stupid and insane ideas, making use of the incomprehension they invoke, with the reference to avantgarde 'thinking': great works of the past were often not immediately understood in their time, and sometimes considered 'insane'; so if I make something totally incomprehensible or insane, this must be a work of genius. A cow is an animal, so an animal must inevitably a cow. Of course, most lemmings of underdeveloped group think welcome such ideas wholeheartedly, because they seem to give credence to their own absurd ideas.
'Sonic art' (the German Klangkunst) was, and for some people, still is, a liberation from any artistic effort. Hence, it is a thoroughly populist form of art.