Imagine a scratch on the surface of a glass lens...
Conventional polishing techniques, like Tetris, roughly fill the free space of the scratch with crystalline particles. Due to the rigid atomic order of such particles, the result of polishing will never be perfect. Consequently, when you look through a microscope you will see microscopic spots, scratches, defects, roughness, and
non-ideality of the surface. All these will harm the use of such material, part, or whole device.
Using polishing technology with amorphous particles represents the future that is already accessible to you today.