Why might it make a difference?
Let's say each one independently is try to handle the same overall market, one with 3 boats and the other with 2. That market is, say, 80% basic diving, 15% more advanced, and 5% tech. They are obviously going to favor the 85% basic market in their scheduling, leaving the more advanced divers out. Let's say they are only able to fill boats to 2/3 capacity that way.
If instead they have 5 boats, they can fill as many as needed for basic dives and have a boat or 2 left over for more advanced diving.
I am not saying that is what will happen, but that is what COULD happen.