The cemetery I regularly go to had so many photo requests and it is not that big of a cemetery. I can walk the whole thing easily in a couple hours. So many are unmarked though.
If you make a request and get the note that there isn't a headstone and then take the request down, the next person to come along isn't going to know that. Which is why I started doing it.
I am glad everyone agrees, I was a little worried people might prefer no photo. I don't know why I thought that though, I would prefer to see this when doing my own research.