Having only a handful of companies in the world exerting enormous control over online commerce is dangerous. The amount of data they control is staggering, especially when combined with data collected from other centralized platforms (social media, the banking system, government surveillance).
I don't like needing to ask permission to use those platforms in order to engage in something as fundamental as commerce. Alternatives need to exist, and OpenBazaar is the alternative to the tightly monitored and controlled online marketplaces.
The world needs a protocol and network for trade that no one company or government controls. That's OpenBazaar.