Why Does POV Matter?
Often writers will report that a reader doesn't mind something like a shift in Point-of-View, that only editors and other writers notice such things. This may be true. So why does POV matter?
A reader naturally turns himself over to the care of the writer. A reader will follow what the writer presents, and will accept it without question as long as there are no glaring issues. Even if a reader does not mind a shifting pov within a scene, that scene will probably leave the reader feeling less than satisfied. The writing will certainly be less than the writer's best.
A scene with shifting POV will divide the sympathy and interest of a reader. A scene that begins in John's viewpoint will involve the reader with John. The reader will likely feel sympathy for John. When the viewpoint shifts to Jane's, the reader must reorient himself. Though there may be no confusion in the reader, there is a diffusion of interest and sympathy. Instead of focusing on one character to develop the greatest impact, the scene loses its power. And to some degree, the reader ceases to care about the characters.