Facebook got their copyright policy straightened out. People were very confused because most people do not understand legalese, or even plain language often times, if it comes down to it.
Here are a couple of sentences I’m borrowing from Facebook, and I’m allowed to do that because I told you where it came from and I am not claiming it as my own work.
“Yes, you retain the copyright to your content. When you upload your content, you grant us a license to use and display that content,” (https://www.facebook.com/help/193430577370347/)
Websites like Facebook and Pinterest need to have your legal permission to host/display your photos. When you post to one of these sites, or any other similar site, you are giving them permission to display the photos or comments you are posting. By displaying your photos, as presumably you want them to do, they are “using” those photos for their own gain.
People come to their website to view those photos that you have posted. When they do, they are subject to advertising. By allowing you to post photos to Pinterest and FB, these websites are luring unsuspecting people to their websites where those people will be exposed to advertising. Pinterest and FB both make money when that happens -- just like we make money when people visit our hubs, and so does Hubpages
Neither Pinterest or FB own the copyright to any of the photos or comments posted, but they do make money off them, and they do need your permission to do that.
If any person tried to confiscate the work of artists or journalists simply by putting a disclaimer on their website saying it becomes their property if posted there, that person or business would be buried, I mean buried deep, in lawsuits.
There is no such thing as stealing fair and square. You cannot steal the work(s) of any person simply by luring people they don’t even know to post their work on your website.
Websites do not automatically become the owners of any image just because someone posted it on that site, but they do benefit because it brings them viewers/readers, which in turn earns them advertising revenue. You are giving them the right to do that when you post something to their site, but you are NOT signing over copyrights to the material.