Excellent article and putting on the table what 'meaning in music' actually might be. Is musical meaning located in the work itself, or does it consist of references towards the world outside the work? My understanding of the article is, that it says that music which has no bearing on the human condition, is mere ornament, more or less chique entertainment, nice after a heavy meal but unconnected to the real business of human existence and hence, easily developed into sonic art which 'means' only itself. But I think it is clear that Debussy never intended to avoid meaning in his music, but located it away from the egocentric 'I' which was cultivated by the romantics. The comparison with Mahler makes all this clear: for Mahler, the emotional experience of the Self was central to his work, while for Debussy, it was the experience of the world that he wanted to render, without the 'I' coming in-between with its emotional outbursts. That is why we have 'Nuages' not as the Self reflecting upon itself during a summer night sky, but as the Self loosing itself in its observation of the sky where clouds calmly sail ahead. So, Debussy's art is, in fact, very modest, forgetting the Self and being absorbed into the world, and expressing the process very eloquently.
This means that this music is very subtle, in psychological terms. In Pelléas, it is not the 'thrills' of nice sounds that form its meaning, but the revelation that the lovers occupy a wave length inaccessible to Golaud, who gets insane with jealousy because on that ethereal level, his wife commits adultery but not in 'real' terms, so she is 'guilty' and 'not guilty' at the same time. To be able to express such subtleties, a music is needed that is capable of expressing meaning with equally subtle means, and thus: meaning that directly relates to the human condition.
With Mahler, meaning is trumpeted fortissimo at every bar, so much so that the listener forgets and excuses his vulgarities, clumsiness and lack of stylistic consistency. It is, anyway, very true and meaningful music. Debussy however, opens a door to much more subtle worlds of meaning, through which we can only enter if we accept that there are more ways in which we can experience meaning in music.
The obvious sensual beauty of Debussy's music does not show that it must therefore be 'meaningless', but in contrary underlines the beauty which is embedded in the natural world, and thus in the human psyche which has developed together with the world in millions of years of evolution. With an amplifying glass, Debussy picks-out the beauty of the world and relates it to our capacity to perceive it, thereby confirming that we are part of the world. If that is not meaning, within and outside music, I don't know what it otherwise could be.
Debussy was, of course, misunderstood by modernists, who lacked the subtlety to hear where this music is 'about', and only perceived the sonic surface of the music. They also misunderstood Webern, who was a passionate and very frustrated romantic, and tried to concentrate the last drops of existential meaning in cristalline constructions, where they easily evaporated under the gaze of quasi-scientific postwar modernism.
The discussion that ensued on SD can be read here: