As you say, they definitely do not have such a big CFD (or any). But they do have a much more accurate flight model, that is inevitable, as the data comes directly from the manufacturer.
Still, even the big sims don’t get everything right, and getting into the real aircraft definitely feels different again. And certainly the scenery on MSFS is much more pretty, although there’s some gains there in the big ones too, but very low poly and low quality textures still.
The flight models we have now are undoubtedly getting closer and closer as time goes on, and 3rd party mods are also helping to bridge that gap even more. MSFS’ limitations now lies in the limits it imposes on itself about the flight model (singular square wing, in conventional configuration is the only one you can have).