@AlexHenry I don't know, that seems a bit of an arbitrary constraint and is certainly very much a personal preference. Clearly, if a bird ended up in a photo, you, at least in some capacity, saw the bird in the field, so how the line is drawn is not quite clear to me.
As to the purpose of ebird, while when read alone that interpretation might seem reasonable, I think in context it's pretty clear that the data collection part of ebird is to assess bird populations and trends, not as a social study on the way in which birders observe. IF you document a species at a location and have photographic evidence that it was there, regardless of whether you noticed it or not it would seem very much in the spirit to include the sighting, as it provides useful information to other birders and scientific study. Now, whether you count that on personal lists is totally to one's discretion.