The trouble is a protein's function is tied to to its solvent, and the small molecules it interacts with on timescales orders of magnitude smaller than a protei

The trouble is a protein's function is tied to to its solvent, and the small molecules it interacts with on timescales orders of magnitude smaller than a protein itself, AND protein complexes up to microns in size can contain strucutres critical for functionality at time scales orders of magnitude larger. There just is no way to accurately simulate across so many orders of magnitude when the effects both above and below it efficiently impinge on that function.