I’m sorry, but that makes no sense to me. It is computationally trivial to split up a mesh if that’s what you want. It doesn’t even require a search, you just do it. It is not computationally trivial to find a nearest neighbor, which is what you need to do in order to weld vertices. That is why I don’t want to impose this burden on my own software when it already has to deal with large models, e.g. 24 million triangles is typical - in the SketchUp universe that would be 72 million vertices to search for nearest neighbors. Even if my algorithm is O(n log n) that’s still a significant overhead.
And it is certainly a bug: if you export to OBJ the vertices are shared, if you export to FBX or 3DS then the vertices are unshared, connectivity information is lost. All of these formats have similar capabilities in the current context (i.e. the can all encode connectivity without relying on infinite floating point precision). They can’t all be an optimal representation of the same model.