Yes there is some nuance here in terms of the data being public but within certain contexts like social media and networking the "data" we are talking about is often in the form of following lists, network reputation, and the ability to operate without being shut down on a whim.
While in theory anyone can process the data and sell it...
I've never heard of this actually happening, yet.
The level playing field makes that model far less viable.
That and it's much harder to tie someone on WEB3 to a legacy identity because the platform does not require such info. The rulesets are completely different and not really comprable. Anyone can create a frontend and give others access to the backend through custom data filtration.