I’ve heard photography pundits say, quite often in fact, that the use of color in a photograph can be seen as a crutch used to disguise poor composition. I agree that’s certainly possible but, I would contend that sometimes color becomes so powerful it can be thought of as the subject itself.
For instance, last Sunday while walking through Boston Public Garden, I came upon this balloon seller sitting behind his wares. I snapped off a quick shot and in Lightroom I cut down on the exposure and changed the format to square. In this case I would contend the color is the photo’s primary subject. (Unless of course baloons are your thing.)