I mean that a piece of art cannot contain emotion, they can be influenced by emotion and they can evoke emotion but the music itself has no emotions. Music has tones and colors and choices of expression, but not emotion. To say music (or literature or visual art for that matter) lacks emotion is a non sequiter as ALL music lacks emotion because music is abstract. It makes as much sense as criticizing a chair for lacking emotion.
A musician can invest much emotion into a work but if the music sucks than the emotion doesn't matter, as we have no way to measure the amount of passion that went into something because passion isn't just making funny faces and saying "baby baby baby". Understand?
Take for example a guitar solo. People may feel like a bluesy guitar solo with a lot of sustained notes and vibrato is more emotional than a fast metal shred guitar solo. But those are techniques to create the illusion of emotion, not actual emotion.
Same as how people equate loud, fast and heavy punk riRAB with emotion, these are techniques, "passionate" vocals with loud resonance and a lot of improvisation, this is also a technique.
Music can sound emotional but it's always because of some kind of technique to give you that impression. "Music is alive" sounRAB poetic and sh*t but it's not the truth, it's just sound.