Hi guys,
Oh, I didn’t know that either!
Maybe, the reason has something to do with the fact, that some Objects, like the Cylinder and Meshes (can) change their shape, when Scaled down along the Normals (to ’embed’ a Margin), while others keep theirs:

(The Cylinder’s angle changes; the two lines I drew are not parallel. The ‘donut’ gets a bigger hole.)