This is simply not true. Although direct modeling is indeed less popular than history based modeling, but this is due to two reasons:
- Modern direct modeling is just 10 years old while history based modeling is almost 40 years old
- Because of this there are very few proper dm cad systems on the market, but actually nowadays every CAD system provides direct modeling functionality, including NX, CATIA, Solidworks, etc. These direct modeling features are used in aerospace too, eg. offsetting a face is a direct modeling operation too.
The confusion might come down to a misunderstanding of the term direct modeling, where many people associate dm with push pull interactions, but these are two different things. A history based modeler can also use push pull interactions, it’s just a more intuitive way of setting the parameters of a modeling operation, instead of entering numbers.
In terms of accuracy, direct modeling is exactly as accurate as history based modeling. If you do the same operations in NX, or Solidworks or Shapr3D, the resulting geometry will be the exact same geometry, with the same accuracy, simply because all of these tools are running on the same geometry engine: Parasolid.
Actually even NASA is using direct modeling tools, and although direct modeling and history based modeling are a bit different, the difference is not the accuracy of the models they create, the only major difference between the two is how they let you modify geometry. History based modelers will let you edit the history (modeling steps) of your design, and “replay” the later steps, while dm works directly with the 3d geometry and lets you directly manipulate features, faces and edges.