I didn't bother reading the article, but I did do something else: I looked up "Solid protocol" and tried to see what it is.
Originally I compared this to ATproto, but according to the Solid website itself, "Solid is a file system for the Web". And that seems to be about all it does, it provides an API for storing data. It has mechanisms for handling encryption keys, meaning that in theory whoever runs the "Solid Pod" where your data is stored can't read it. But you've basically created a standardized method of accessing OneDrive or Dropbox or any other number of cloud storage providers at that point.
This feels like a whole bunch of API specifications that simply implement a cloud storage service. Sure, all your data may be in "one place" and in theory you can then download it all and move it somewhere else, but in practice you'd still be accessing it through other services that presumably can read it. Assuming this is supposed to be able to provide social media services, these third parties would still be able to determine what you see, whether for advertising or more nefarious purposes.
Again, from the Solid website: "The Solid ecosystem is built on a simple but powerful idea: separating applications from the data they create." Why would applications agree to do that? Even if they do, how you can you be sure they don't save a copy? Even if they don't save a copy, how do you prevent them from using the data that passes through them to track you?
This seems to be a whole lot of added complexity that doesn't really solve anything.