The importance of cross-patterning motions such as crawling and walking has been understood for many years.
Among other benefits, it enhances communication between hemispheres of the brain.
To illustrate the point, try walking such that your same-side arm/leg move in the same direction at the same time (homolateral gait).
Even a few seconds of this will briefly make your muscles weak from head to toe. Have someone test you if you doubt it.