Steem data is still possible to sell. The data is worthless when it's disorganized. Those that organize the data in a way that can make someone else profit will be paid.
Also, we can make whatever data we like inaccessible by encrypting it. Anyone with access to that data could also turn around and try to sell it.
Well anyone can access it via the blockchain, but yes it's not organized. A company could pull the data and sell it indeed.