Comment by zamadatix

The "The Traditional Way" section of the article covers the shortcomings of the WebRTC approach (i.e. ICE) and why it does not always result in a P2P session forming/the TURN server leaving the picture.

The tldr is having a TURN server enables more hole-punching methods to be attempted, but that's not the same thing as a guarantee the session will succeed in switching to P2P.