In the Myth of Viral video blog post, I discuss the catalyst. Everyone thinks things just happen and that things naturally go "viral" if the content is great. This is not true. Everything needs a catalyst before it moves anywhere. An atomic bomb does not detonate until someone pushes the button, whoever pushes that button is the catalyst.
Even great artists need to be promoted through a variety of marketing channels before people can become aware of who they are or what they do. For example, you could have a mainstream talent coming to town to perform at the stadium. If the stadium does not put their name on the marquee, nobody is going to know they are there. That marquee, radio advertising, newspaper article or whatever became the catalyst.