Well I don't know what the writer's exact reasoning is, but there are few factors for why larger rooms are favorable: 1) Room modes. Small rooms are far more d

Well I don't know what the writer's exact reasoning is, but there are few factors for why larger rooms are favorable: 1) Room modes. Small rooms are far more destructive because they feature hot-spots where the sound waves (especially the low end) are either cancelled out or reinforced in a way that makes them too loud. Large ceilings and lots of the depth to the room give the low frequencies space to propagate completely and a more even frequency response that isn't lumpy or lacking when you stand in certain parts of the room. 2) Reverberation. Pretty obvious, but the average length of the echoes/reverberant tail increase as the room gets bigger. This is gives an ambient quality to the sound that is well suited to orchestral ensembles. You could probably argue that the history of orchestral composition grew in tandem with this quality and informed the choices that were made or play best with the qualities of a room large enough to house an orchestra and audience. That said, highly percussive music might be muddied or hard to articulate cleanly if it's fighting against a massive reverb tail in a cathedral.