I’m basing that on things like this: DirectX 12 Can Push '6 to 12 Times' the Polygons of DirectX 11 - IGN - apart from this, it doesn’t seem unreasonable to expect polygon counts to continue to grow as they always have. I’m just finding that the tools are not keeping up.
That’s 500k for one object. The 2 million poly object is broken up into about 8 pieces, although I’ve been telling UE to merge the mesh on import.