I do think that's true, which is why I'd call this something like "plagiarism" rather than "stealing". The issue isn't that anyone's had an item removed from their possession (as with theft), but someone is trying to pass off someone else's work as their own. Like if I were to publish a novel, but lift large parts of the novel from an existing novel. I guess you could colloquially say that I've "stolen text" from that novel, much as people say that Microsoft "stole" the recycling bin from Apple's trash can, but plagiarism seems to get at the underlying issue more directly.