The notation OP is using is relative to the key of your song. So if your key is C major, the V chord is G. However, if your key is F major, the V chord is Bb. So it's not that there's only a few chords used in popular music, it's that there's a very consonant group of chords for any key your choose.
Also, OP is leaving out lots of ways to modulate these basic chords into more complex ones (adding a seventh step, inversions, power chords, etc.).
Finally, as with a lot of pseudo-Pareto type things, often the few exceptions are what make or break a piece musically.
