The Funnel (Updated)
The basic premise of how marketing communications works is that it is a process by which the marketer takes the consumer through the communications funnel. Historically, that was a one-way communication (often called "The Funnel") with the marketer leading the consumer down the path from awareness to sale. With Al Gore's invention of the Internet (prior to his Global Warming crusade), all that changed. Now marketers must understand that marketing communications is a two-way conversation.
Note in the above diagram, that there are roles for mass media as well as one-to-one communications. The idea here is that the strongest and most enduring communication plan includes both. Limiting yourself to just mass media may enable you to reach a lot of people, but it puts the burden on the consumer to engage in the conversation with you. On the other hand, utilizing just a one-to-one communication dramatically reduces the number of people you are introducing to your product or service. In fact, without the broader "introduction" mass media provides, between privacy concerns and the skepticism many have with advertising itself, utilizing only one-to-one communication could turn off potential customers.
Think of this process as somewhat like building a relationship with a significant other; a one-to-one connection via Tinder may accomplish a short-term goal, but a more formal, old-fashion introduction, exchange of information and courtship will lead to a more permanent relationship.