The most important reason to use a specialist operator is the expert advice that is freely available from them. This takes two parts.
First, practical advice and specialist knowledge on where to go and what to do, usually with a level of insight well beyond what you might get online. Whether it is knowing what the local game-viewing is like, what the camp layout and atmosphere is like or how meals are prepared, an experienced operator should be able to give you detailed information because he or she will have visited the camps you are considering. Over the course of a career, some specialists will have stayed at most camps multiple times, and at different times of year.