Musical tone consistency is also important so people can do music together. You want some consistent voices, or instruments working together. Two guitar players with one out of tune is going to be very noticeable, as would be one person singing the wrong notes in a duet's chorus part.
However, go into a museum gallery of photography. You'll find grays all over the place. You might even find different tints of mattboard and framing material between photos. Nothing is super consistent, just like the subject matter. If it looks good and relevant, it gets hung on the wall. It doesn't have to be accurate in any way.