This is a good point.

When I worked with Deda they had a batch of bars that could have failed this way if we hadn't caught it.

The problem was that the carbon bars were to spec out of the mold but once the non-slip coating and clear coat were added they were quite a bit larger than tolerances would allow.

Clamping these bars (even with a perfect stem) would have resulted in failure.

Looking at the photos this might be another possible answer.