In June 2014, I was asked by Google to go to their offices and talk about the ideas of the Curve to a room full of etailers. It was part of an afternoon when Google pointed out that ecommerce providers in the UK have three times as many page views as every newspaper and magazine in the UK combined. They are fixated on conversion rates and sales, yet they offer a enormous, free, value-added resource to their customers which can be harnessed as a revenue strategy (through advertising) and through a Curve strategy (through content marketing, earning the right to talk to their customers again and enabling superfans.)
One of the key tenets of the Curve is that you use free to find an audience and earn the right to talk to them again. A content marketing strategy that just finds an audience with no follow-through is not a strategy.
My preference is email, because it is in my control, but it is important to be where your audience is: YouTube, Twitter, Pinterest, Tumblr and so on.
I have long joked that Facebook is different. On FB, you are “earning the right to pay Facebook to speak to your fans”, and their ongoing changes like hiding the most recent posts and encouraging users only to see the posts that Facebook wants you to see are part of this monetisation strategy.