I guess that, at least for me, it's more a question of whether or not any post adds value. A great photo of something can definitely add value. A slightly out-of-focus picture of a bowl of chips posted six times from different angles does NOT — IMHO — add value; it more reeks of an attempt to "reward harvest."
Personally, I don't use Instagram much because I find it pretty boring... I want to know the story behind a photo, not just see the photo.
=^..^=
I totally agree with you! It can't just be a photo, there must be a context, but I don't believe that context needs to be an article. And I believe that Proof of Brain has space to value and support the idea that photos can indeed be good content. Of course, you would have to be careful with spam, but still, I find something interesting to think about.