the pinning and re-pinning so that the original person isn't getting credit for their idea. I've read several people talking about having their things pinned and people misusing their ideas or pictures. OR not giving credit so it seems like they are original ideas.
Some people don't care. It's fun to share! I can see why you would be concerned about pictures of your kids or original ideas that you are making money from, though. The watermark at least prevents people from printing your picture and selling it as their own- which apparently has also been an issue.