literally almost all music ever created within the last 100 years is based on a simple 4 chord progression.
this isn't true at all, there are thousands of pieces of music from the past century which go well beyond 4 chords. most jazz, classical, folk, and lots of electronic music use way more than 4 chords per any piece of music. it's rock, pop, blues, and dance music which usually have low chordal diversity-- but because these are the most popular genres, they are probably what you're most familiar with. (and that's ignoring the exceptions to this trend too)
