[lux]

The reason people fall back to the I IV V and VI chords (C F G and Am in the key of C) is that going between them creates a false sense of forward motion in the listener without actually going anywhere. Moving from the IV to V creates tension that can be built up and released by resolving to the I, or increased by going to the VI and resolved to the IV. Any combination of those pretty much sounds "good". Variations add the II (Dm) in place of the V or in between the IV and V, or add the III on the way to the IV. It's really simple, and made even simpler by power chords because you don't even have to move your hand shape to play entire songs on rhythm. Leads can then switch between major scale phrases and pentatonic (aka blues) phrases of the minor of whatever key is being played in, (so Am blues over C) and almost anything they do sounds good to the average listener. In the end, you only have to keep their attention for ~40 seconds between hooks and just crutch on the catchy chorus and you've got a hit. But if you analyze most popular forms of music, the above is at their core anyway. It's just more bare bones in modern pop and rock music.