So one overwhelming conclusion is that threadless would work best, if bike manufacturing tolerances were up to spec.
So that leads to the crucial question; what can bike manufacturers change in their processes to match the required tolerance levels? Is there a quick, straightforward fix that can be implemented to carbon mould assemblies, metal welding rigs, etc, that will guarantee that the BB shell is always perfectly round and aligned, and won’t flex under pedaling loads? And if so, why don’t manufacturers implement it?