Dawes-Man, in your original post you said they broke during low speed. Low speed does not mean low stress. The link's break occurred at low speed but high torque because he was trying to accelerate when it broke.

The cumulative fatigue from "10 million" low stress cycles can be completely overwhelmed if you give it a few high stress cycles (such as when you are trying to accelerate). Add in a few manufacturing defects and use a brittle material and you get a cracked spindle.

Is Chombi pulling our collective legs, or is that a real story?

This thread is making me want to disassemble and inspect my old pedals.