Steven Shattuck is spreading the word that while social media platforms are useful, you don't want to be over dependent on them. You want to own your own content on your own Web site too.
Quite simply, digital sharecropping is the act of using a third party platform to publicize your brand. The brand creates the content and publishes it on an external platform in exchange for exposure on that platform, similar to how sharecroppers would tend land owned by someone else in exchange for a share of the yield. The tenants do all the work while the landowner reaps a majority of the benefits.