Originally Posted by PeteHski

You've lost me now. I wasn't disagreeing with anything you've said. You stated in response to what someone else posted. "I don’t agree. If anything the damper would limit oscillations of the frame and change the mechanical resonance".
I just pointed out that it's actually a spring, not a damper (although it may have some self-damping). Neither of us would know what the effect of that additional spring is, we can only speculate. My own experience of undamped springs in the automotive world is that they make resonance effects worse. I would have thought that was quite a reasonable view, no? It's one of the primary reasons why dampers even exist.

Trek engineering might not have looked that closely at resonance, presuming it wasn't a problem in their field testing. But if they did, then it didn't really help the OP and at least one other poster who had a problem with this bike.