Quo have ridden the standing joke that they only use three chords, and made a higely successful career out of it thank you very much.
The Quo Army do resemble a football crowd with their chanting, and penchent for undemanding rock-a-boogie, but to label them as 'thick' is to do them a mis-service.
Besides,. as France Rossi said to me when i interviewed him - he knows three major chords and three minor chords, so that is six chords!
So tell that to their detractors!