Photographs are praised for being the most realistic replication of the subject. However, they rarely do so. Much of this is due to things beyond our control. For example, the range of light in the subject is often greater than in prints. Displaying transparencies can reduce this problem, but may be impractical. Many decades ago I usually displayed photographs as projected Kodachrome slides. They may not have realistically replicated the subject, but they were impressive. Then it became practical to set up a darkroom, and B&W prints became my norm. Nature has color: those prints did not. This sometimes required using filters to separate elements in the subject that were easily differentiated by color. Also, prints usually had less contrast. B&W negatives and prints had reduced contrast in the darkest and brightest tones, emphasizing the contrast in the middle tones to restore a resemblance of the subject. We accept this distortion as normal.
Sometimes the purpose of the photographer is not to present a realistic copy of the subject, but to evoke a response that may have little connection to the subject itself. Then the rules may be disregarded: anything goes.
Manipulating photographic images satisfies both of these approaches. It should be minimized in some technical and journalism fields. In realistic photography a good goal may be: "Honor the subject." In some photography, the photo is more about the photographer than any thing else. Then anything goes. Who else cares?