The ability to split an edge and thus to create a vertex is especially useful in the context of faces and face parts.

When creating new faces you can specify 2D geometry plus the edges of face parts and solid parts. If you don't want the new face to extend along the whole length of the edge or 2D line, you must split the edge or line and insert a vertex.

The splitting of edges works on the edges of face parts, solid parts, and 3D curves.