what a load of crap, lyrics were always important, this evidenced by the fact that people wrote them. do you think the lyrics in operas were not important? how would anyone get the story then...
technical ability....jesus, people spent centuries or millenia sucking ass technically. the modern instruments are much easier to be consistent in.
the only form of music where the scale mimics the human voice, aside from every form of music.
honestly if you think music was invented in the united states and didn't exist before the invention of recording technology this makes sense.
the good thing about blues is that it's good, good enough that it doesn't need made up and ridiculous statements to justify it