The internet changed everything. Whether one agrees with this statement or not, the fact is that the internet changed a lot. For customers, it changed the way we shop, socialize, and search for information. For businesses, it changed their business models.
Technology has traditionally been an enabler of business models and capability. By changing them, this new technology called the internet became a driver of business.
Over dramatizing albeit just a tad this type of technology that is a driver of business is being referred to as disruptive. The disruption here is in the order of things. The reaction is to change them to adapt to conditions created by the technology versus the other way around.
Wikipedia Definition >> (as you can see, I have taken a different - business focused - view to this term)