Expeditionary groups should always function as a team, and the job of their leaders is to make sure that they do; newcomers usually bring new ideas an additional capabilities to established teams, but not without problems.
There are different kinds of personalities, habits and ideas, and among explorers, adventurers and extreme athletes human nature also does its job of dividing or joining together people, like in any family, business company, traditional sports team, and so on. Some people are more individualistic than others, but exploration and extreme activities in which more than one participates, there is no room for egos and hormones. It is a rule of thumb that those who are unable to work as a team under extreme conditions tend to fail or even perish.
The best kind of participants for any sort of expedition are those individuals who have worked together in the past; adventurers who know themselves and have taken part in other expeditions before will seldom cause trouble. People who have no clue about expeditionary teamwork because they are completely new to outdoor activities may cause some problems, but due to their lack of experience; such people are usually receptive to suggestions or commands given by those who they see as evidently more experienced than themselves.
But the really problematic ones will usually be those who already know something but have little experience working in a group or are completely knew to an already-established team, no matter if this team is constructed on a formal or informal set of rules. People who already know something have also developed habits and criteria that are difficult to change in some instances, and they might also feel superior and more skilled than the group taken as a whole.
Solo adventurers tend to be more efficient in some aspects than a team: they can decide when to get up, start hiking, when to stop for lunch, where to camp and so on. They never have to wait for others to finish preparing their backpacks or for someone who is walking slower than the rest. So, when the time comes to make superficial comparisons, such newcomers may indeed start feeling that they are actually better than the team that they have just been introduced to, forgetting that the kind of projects and goals that a team can set for itself are completely different and far more ambitious than those that a lone ranger can conceive as feasible.
No solitary astronaut could have reached the Moon, and even Hillary required of a whole expedition to reach the summit of Mt. Everest. Group and team leaders should always stress this, especially to newcomers.