Sorry, I don't see the analogy.
I wasn't asking how a knife wears.
Perhaps I didn't ask my question very well so let me try to illustrate.
Let's say a knife has a hardness of 60 HRc. At the top of the spectrum we have glass and granite. Let's assign an arbitrary hardness of 100 HRc for them. Since glass and granite are much harder than the knife, those materials are detrimental to the knife's edge. I don't think anyone hear would argue with that.
Now looking at the the other end of the spectrum, wood and polycarbonate. Both are too soft for the Rockwell C scale. So let's just switch to Rockwell B and arbitrarily assign a value of 20 HRb to wood, well below 0 HRc. We generally consider wood to be a preferred material to cut on. So where does poly fall? If the hardness is near that of wood, then the two material should perform near equally. It seems to be generally accepted that poly is significantly harder than wood and therefore more detrimental to an edge, but is that true?
But the wood part of the equation is complicated a little by the use of resins and glue. What is the hardness of the resins as compared to the wood and poly? I would think that the resin hardness is about equal to that of polycarbonate so I would not think there would be much difference between the two. However on these Epicurean boards the consensus seems to be that because the resin content is so high, the boards are hard on knives.
The silica content of bamboo is an excellent point as mentioned above and kind of differentiates those boards.
It seems widely accepted that these Epicurean boards are significantly harder and therefore knife contact should be light. I'm wondering if that is just an assumption that has been taken as fact. I haven't seen anything to support it and if the resin hardness is on par with polycarb then the two styles of boards should be about equal.