I had a light-hearted argument about this with my wife as we were at a museum. I was just walking around taking pictures of cool stuff. She was baffled, and insisted one of us had to be in it at least. And I'm like, I'm trying to take a picture of a thing, why would I also be in it? I don't have social media, the only utility of these pictures are for me to look at later, show my kids, or maybe send to a friend. And that's where I found the dividing line. Who is the photo for? If it is just for private sharing and looking at in your camera roll, there is absolutely no reason why you need to include yourself. Anyone who looks at it will know the context that you were the one taking it. Its only online strangers that there's a feeling that more context is needed. Or that we need to openly show that we are smiling and having a good time at the place.