If they spent some time trying to learn more than two or three chords,
You do realize that 98% of popular music is based on three chords, right?
Everything from Matchbox 20, Stevie Wonder, Al Green, Nirvana, Madonna, or even Nickelback and Sheryl Crow....it's usually just 3 chords. Maybe a 4th chord added in for color, but for the most part it's still 3 chords.