From what I understand that’s more or like what they did in the new technology.
The tessellation is changed based on the distance from the camera.
So it’s basically an LOD for tessellation that is innate so that artists will not need to bother to make different version for each object.
As for amount of triangles - it is very important to keep it very high since you want to realize which point is possible to be viewed from the angle the camera is watching.
For example:
If you look at a rock behind a sphere - if the sphere is not rounded enough a few of the triangles from behind the sphere will not be seen and the same for the rock which is even further, the rock might have a small bump that goes over the sphere and will not be seen if you reduce the triangles too much.