They didn't have the Holy Spirit. Music of repetition, emotion-building, occult tendencies, and have been dragged down into apostasy. A good part of it, through the songs we sing. Remember Plato's words, how songs have more impact on a society than jurisprudence. Same is true in the Church.
People remember words of songs more than they do sermons.
If the songs contain false doctrine, people learn false doctrine. Again back to where this all started. Same as if I fed poison to 1000 people. Think about it.