kn you are spot on i reckon...its ALL marketing!! even if you are a singer/songwriter trying to develop a fan base you are in effect marketing your stuff, its just to a much smaller audience...a+r people usually look for something that is already a market proven sales generator... not many, apart from independents (god bless em!!!!) will try something different unless it already has follow on underground/indie circuits..
and to scott, i reckon that the peer pressure angle is a reality, certainly taken advantage of by the majors.