What is stolen and what is not stolen?
Material PUBLISHED openly on the web - it is hard to protect that. As much as some picture and/or story published in a paper or magazine. The moment it is open source there is no judge who will interfere, with the exception if it is further commercially used.
That is the difference: are you using it commercial or not?
Taking (stealing) from closed channels, paid channels, that is infringement of copyright.
Nevertheless it happens. Moviecompanies stealing ideas, manuscripts are ver hard to protect, Music companies stealing from long dead composers, Google and Amazon stealing books for scanning, they are too big to sue them.
It is part of life.