I'm not sure exactly what theories they're referring to here, but if you listen to an avant-garde musician like Stockhausen, you can still hear incredibly beautiful melodies and progressions and rhythms. They're just very different from the norm.
Serialism does not mean non-melodic. Procedural creation of music does not mean the melodies and rhythms "don't exist". If anything, they're more there than they are in traditional music.
If anything, they're more there than
they are in traditional music.
It's the same if you talk about seeing
structures in old terrestrial tv noise
patterns.