Comment by sophacles

I understand the technical aspects of it. There is still no guarantee that they delete the photo. They say they do, and I don't seriously doubt them, but the possibility exists that they keep them around for whatever reason. Further, there is a real possibility that an attacker could find a way into the Instagram systems or hijack the communication streams between users and the servers, and then you have a leak. It is a potential privacy concern that is caused by the "upload everything and throw away some of them" algorithm.