why churches should ban singing in harmony

I recently reviewed Life Together by Dietrich Bonhoeffer.

What I liked:
1. "The ministry of holding one's tongue" (p.91-94)!
2. Work should be "a real breaking through the hard "it" to the gracious Thou" – in other words, it should be God-centred. (p.71)
3. The view of fellowship as a kind of sacrament (p.20) and the potential of confession to build fellowship (p.112)

What I didn't like:
The extraordinary section on singing – I could hardly believe what I was reading! "There are some destroyers of unison singing in the fellowship that must be rigorously eliminated … There is the solo voice that goes swaggering, swelling, blaring, and tremulant from a full chest and drowns out everything else to the glory of its own fine organ." (p.60)