Couldn't a federated system that looks like a centralized system work? What if something like Diaspora just installed itself on an AWS EC2 instance for you, and you only had to enter a credit card?
Compare:
"wordpress.com" (hosted): "Create your new website for free. WordPress.com is the best place for your personal blog or business site. Create Website (button)"
"wordpress.org" (download): "The latest stable release of WordPress (Version 4.5.2) is available in two formats from the links to your right. If you have no idea what to do with this download, we recommend signing up with one of our web hosting partners that offers a one-click install of WordPress or getting a free account on WordPress.com."
Open source just doesn't get user-friendly onboarding.