You missed the point. It is not about if it is private or not, it is how they use it.
You are allowed (on some pages) to read news article. Are you allowed to copy and publish them on your own site? No.
You have a Copyright on your posts same as a author has on his books.
If it is legal or not is still to be discussed.
Similar to how data was mined (or even still is) about users without consent. Now there is for example the GDPR.