[Kesty]

It's a classic point in most, if not all, social websites or where the content is generated by the user.

And it's usually there to protect the website for altering storing and advertising with user generated content.

It always has had the potential to be used for bad, we will see if this time actually happens.

[delinka]

"Royalty-free" doesn't mean they can just do what they want. It means they're not going to pay you for the things listed in the license (to which you agreed by hosting on their site.) It doesn't even say "...perpetual license." It's clearly limited to stuff you've put on their systems, while it's on their systems. You remove it, they can't use it.