Rambling Tinfoilhat speculation:
We seem to get information that K'aresh had also a "radiant song" shortly before it was destroyed by Dimensius.
Now, we think that the radiant song is from Azeroths world soul, right? Well, perhaps not! This is what Magni, the speaker of the world soul says:
https://www.wowhead.com/news/the-rad...poilers-338772
Magni: "Speaker of Azeroth". Bah. She hasn't been speaking to me.
The one person who should be able to hear the radiant song, doesn't hear it? And if he tries to connect, he get's a backlash.