Reason: It's easier to play these chords on a 6 string guitar, which has been the dominant instrument of choice for pop song composers.
The first C chord on a guitar is easy to hit with no finger twisting required. It's also easy to switch between the first C, Am, and G chord, you can even do it quickly and repeatedly while drunk as you can imagine many pop songs are written. The first F chord requires a little more careful finger placement but still easy to get too. Sure enough you hear this over and over in pop songs, some simple sequence of C F G A chords over and over.
Not surprising that the complex guitar chords that require six pencil-thin rubber fingers and a degree in music theory to know how to play aren't heard as often.
The first C chord on a guitar is easy to hit with no finger twisting required. It's also easy to switch between the first C, Am, and G chord, you can even do it quickly and repeatedly while drunk as you can imagine many pop songs are written. The first F chord requires a little more careful finger placement but still easy to get too. Sure enough you hear this over and over in pop songs, some simple sequence of C F G A chords over and over.
Not surprising that the complex guitar chords that require six pencil-thin rubber fingers and a degree in music theory to know how to play aren't heard as often.