Monoculars have been used for centuries for spotting far away objects and improve the human sight. There exist accounts of ancient monoculars used in Arabia. Napoleon always carried one with him. A monocular offers a more condensed and precise view than binoculars. One of the main differences between monoculars and binoculars is that monoculars only have one lens barrel, while binoculars have two. This means that monoculars can be a better option for people who have vision difficulties in one eye. Why?
The brain down or up regulates eye vision for each eye to have a median and balanced view. There is a lot of processing goin on in the background, so to say. In the case one eye has superior vision, the brain inhibits the eye that has inherently a better sight and/or tries to improve the eye that has inherently weaker sight. Of course there is just so much that can be done if the lens and light angles are not optimally directing light to your retina. Nevertheless, there are muscles controlling your eye movement and lens dilation, which can be used to optimize that organs function.
This costs processing power and can be the root cause for headaches, migraines and other conditions, if the differences between your eyes is significant. Naturally this mechanism prevents you from fully unlocking your eye sight potential for the good eye, when both eyes are used. Glasses can correct this issue for the majority of the time, but it cant be 100% cured. With a monocular you can circumvent this issue and enjoy a higher degree of visual detail than you would be able to with binoculars, because your brain can fully concentrate on one eye. Having slightly different eyesight between eyes is natural and even present with completely healthy individuals. Therefore, using a monocular with the stronger eye, has many benefits.
Further, even compact binoculars such as 10x42 or smaller are clunkier and heavier to carry around than the Python HD, which can be refracted into a perfect pocket size and carried around all day without the help of a binocular harness.