Your name is on the mission....they can still do that even without the button.
Yes, but having a dedicated button only encourages such as it makes it so much easier to do so.
In fact, I would like the option to review as annonymous. I have a feeling that some reviewer are going to have some people take revenge just because they give an honest but negatitive review. No being able to see a reviewer would at least minimise those looking for revenge.