Oh man, can't wait to post a full book of the lord of the rings as a facebook post and make it legal for facebook to use it as training data. Words can absolutely be copyrighted/licensed, otherwise books and scientific journal copyright/license is BS too. Big company however, usually has EULA that states you as a user grant the company the right to basically do whatever the fuck they want to do with your content. As much as I'd like that to be a reality especially for millions of research paper, but the current reality is that copyright law sucks ass.