The pentatonic scale is the guru of improvisers. And it is not hard to discover the reason why everybody uses and abuses of this scale: It is easy to create and to use. Some decades before, some musicians use to earn millions just playing this scale. Today is not too easy to become rich just playing the pentatonic scale; therefore any beginner musician learns how to play this scale (and generally spends the rest of the life doing only this).
Learn more here: http://www.simplifyingtheory.com/pentatonic-scale/