This gets back to the question I posted at Big picture server question, which is, really, about ownership and control of one’s data. The appeal of Solid for most people, I think, will be that it allows them to gain control over their own data. But how is that possible if they are just taking their data off, say, Facebook, and putting it on a Solid server run by a stranger?
The answer in part, I’m guessing, is to make it easy for users to move their data from server to server. Granted, most of us won’t do that often, but knowing we can gives us that sense of control.
An analogy might be how we use cloud sync and storage services now. You can easily cancel your service with Company X, move your files to Company Y, and all is well. You cannot do that now with your personal data stored on Facebook. So even though, with Solid, most people will still be relying on, and probably eventually paying for, Solid providers (unless they want to run their own server), they will know that they do indeed control and own their data, and that’s a good thing.
Ideally, in a perfect world, IMHO, the best thing would be for us to have our personal data on our own devices and machines and choose how and when to share from them, but that will not be the case with Solid, according to my understanding. And, let’s face it, for devices to be able to share files, they have to be on all the time, so there is a place for central servers and there always will be.
But the plan to win users will include the advantage of taking back control of what is yours and what most people, naively, gave up their rights to.