IMO, my son-in-law achieved very decent images with a minimum of gear because he had contracted for an individual safari vehicle for him and his father to shoot from. This was expensive but went a long way to ensure that he could get decent images.
I have seen images of safari vehicles that are so crowded that IMO, even with top-line gear, if would be difficult to achieve top-line images. And it would be frustrating as heck for me to try that route.
If I can make an analogy: Here in California we have several ways to ocean fish. The least expensive is the party boat (often called a cattle boat) in which fishermen are lined up elbow to elbow along the rails.
This is IMO a terrible way to fish since many of our fish are relatively large and fight extremely well. This results in tangles and lost fish. Additionally, since the party boat is the cheapest way to fish the ocean, many of the fishermen aboard are inexperienced which increases the line tangles. A private boat or a six-pack (commercial boat with six passengers or less) is a far better (but more expensive) way to go...
I would assume that this would also be applicable for a safari photo tour. Riding in a vehicle with six to ten (or more) other photographers of various experience and shooting with P&S cameras and cell phones would be as frustrating to me as fishing on a "cattle boat". I would rather not fish than fish on a "cattle-boat" as I would rather not go on a safari if all I could afford would be a "cattle-vehicle".