With a background as an artist and graphic designer, I would assume that whomever posted their copyright information in the middle of their hub, would be doing it for the same reason that an artist/graphic designer would put a watermark type name/image over their original artwork - when it is published. This would keep someone from cutting and copying the entire article and pasting at their own. However, if someone knows how to edit... then this is not going to stop them from nabbing your article.
I had a back handed compliment, when I was googling one of the subjects that I write on - and found that someone had plagiarized the beginning of my article without giving me credit. I'm sure this happens all the time, but that seemed like a historic day for me-- because at least they thought that my writing was worth copying and claiming for their own... but I never got credit for my own thoughts and words.
How can you stop this? With today's technology, people can swipe anything that they see on the internet and claim it as their own.