If a camera wielding diver finds some interesting subject and wants to spend an hour photographing the subject, what's the big deal? I'm likely to find something else interesting that the photographer won't see.
It depends upon the dive plan.
I was on a dive in Thailand that sounded really great from the description of it. We were to follow a specific path, led by a DM, and surface in a large cavern with beautiful formations. (To be clear, this was not technically an underwater cavern--there was air space.) We would exit through the cavern, where our chase boats would be waiting for us. We were split into two groups, and our group was the second one.
One member of our group was a photographer who delayed us taking numerous shots of one critter before finding one that he really wanted to photograph perfectly. We all explored the area around him for a very long time and saw absolutely everything there was to see there more than once. The DM leading our group was new to the business and did not have the necessary body parts to get that guy away from his subject. When we were all finally low on air, we surfaced where we were and got picked up by a chase boat. We never got to the cavern.
Back on the liveaboard, the people in the other group were raving about the beauty of the cavern. Our photographer was raving about the shots he had gotten--over 120 in total. I said I had really hoped to see that cavern. He said, "Not me! I'd rather take pictures of a living creature than look at old rocks any day."
And so he had his preferences, and the rest of us had ours. Of course, ours didn't matter, so we all had to scrap the dive we wanted to do so that he could do the dive he wanted to do.
At the end of the trip, he announced that the photos he had taken on the trip were for sale. I am pretty sure he got no buyers.