There is no question that social media of various flavors can be a useful tool for marketers. But it for sure makes lots of money for the social media platforms. The more users of Facebook, YouTube, et al, the more money those companies make. This title from a recent Advertising Age article probably says it all: Old Spice Killing It On YouTube Again, But Sales Are Down Double Digits.
Professional marketers need to focus on producing outcomes, not outputs.