I haven’t got that far, but here’s what I have
Solid is a specification for servers. The Solid specification is intended to describe servers, also called pods, that are as simple as possible, but no simpler, that will provide access to data resources by WebId in a hierarchical file like way or with Sparql queries, with notifications on changes.
WebId’s are the new thing that enables Solid. They are how people can identify themselves on the web. A WebId is a uri, a link, to a profile that describes a person or an agent that can access resources on the web.
A WebId is not a government issued id. It is more like a persona, one that describes the person or agent to a pod or pods. It is invented by its owner. It identifies that owner only according to its use with a pod. So you can create any WebId, but if a pod knows you by a WebId then you must consistently use that WebId in order to claim or grant access to any data you put on that pod. You can have any number of WebId’s.
Data on a Solid pod can be associated with a list that controls access to it by WebId. The list can be a complicated recipe involving one or many WebId’s. Each resource on a server can have its own access control list, or lists can be applied to containers of resources.
In this way, Solid servers can give rise to many client applications that have all of the features of current social media platforms, and more than that, access to each item of data can be designated for exactly specified users or groups of users. This will cause data silos on centralized servers to be broken up into small servers for each individual or project where data access is controlled by that individual or project.
Solid will precipitate an inversion of control from the current regime of powerful centralized servers and simple clients. Client applications will aggregate and present data according to the WebIds that they have authenticated, and they will become bigger and more highly evolved, and servers will be simpler and smaller and more decentralized.
So how are, to take one example, user comments, better on Solid? The short answer is they aren’t. Yet. Because the apps are not built yet.
But they will be. And user comments will be better because each user can have their comments on their own pod and have complete control of them. No one can delete them. Only those of the users choosing can even see them.