That’s an interesting question in principle (even if there are some clear legal directives). You can try to reconstruct a user profile even just from a list of

That’s an interesting question in principle (even if there are some clear legal directives). You can try to reconstruct a user profile even just from a list of commonly visited subreddits. It can help gauge age, location, personal interests and political convictions. And if you have access to the content of the messages, well, even doxing may be possible.