I disagree.
Henry Peach Robinson argues that while a photograph must be "True" it need not be "Factual". This is a quite old and conservative point of view, much photography since his time has been neither. In any case, he suggests that a picture should, essentially, be credible and believable. Whether it accurately represents a single configuration of objects present in front of the lens in a single instant (i.e. is Factual) or not, it should represent something the viewer can easily image was present. That is, it should be True. In the 150 years since then, we've seen a great deal of successful photography that's not even True in any sense HPR would recognize (cf Man Ray, etc).
A good part of Robinson's rationale is simply that emulsions of his era could not be Factual. You had to choose between Sky and Land, and so composites were used to get them both in the same frame.
To extend Robinson, it is in fact absurd to insist on Factual representations. When you imagine that you are taking a true and accurate representation of what was in front of the lens, you are kidding yourself. Your picture is, for starters, flat. It generally does not accurately render either the tones or the colors. In general, your picture can be and has been made a better picture, often a Truer picture but a less Factual one, by burning and dodging and other relatively mild manipulations (cf. Adams, etc).
To draw a line arbitrarily in the sand and say "these manipulations are ok, and these are not" is the absurdity.