What's with the request for a picture on Facebook? [View all]

I joined Facebook strictly for the purpose of joining a group I was in. I gave minimal info about myself, but was able to join the group. I read stuff on it for a day or two. I can't remember when I made my first post, but today when I tried to log on I was told I'd been shut off. I'm sorry I can't remember the exact language that was used. I clicked a button to request a review. I was sent to a place where they insisted on a cell phone number, so I gave it. I got into Facebook and posted some replies to existing posts. Then when I tried to post a new message (in a group - don't know if that kind of post is different), I got the same shutoff message. This time Review insisted that I give them a picture. They said it would only be used once, for this purpose and would not show on my profile. So I did. I got back on Facebook. The picture is not on my profile.

My question is this. What use to them is this picture? What was going on?????

Thanks,
AG