The quote from David Roberts, a long-time mountaineer, describes how the appeal of mountaineering, in part, stems from the fact that the real focus is the challenge of climbing the mountain. The magnitude of that challenge makes interpersonal relationships seem insignificant by comparison. The challenge also makes people into comrades pursuing a shared goal together, even if they have little in common when they are not on the mountain.

In other words, the shared goal of getting to the top of the mountain creates a bond among climbers even when no other apparent bond exists. Krakauer refers to “the freedoms and pleasures of the hills,” that can create short-term friendships just by virtue of people being together on the mountain.

However, even within the book itself, this concept is disputed. One example is in the description of one of the climbers: Sandy Pittman. Krakauer paints Pittman in extremely unflattering ways:

An indefatigable seeker of public attention, Sandy made her name and picture regular fare in New York society columns.

He also depicts her as egomaniacal, oblivious to how her behavior impacts others, and completely out of her depth. He writes:

Upon arrival in the Himalaya, Pittman appeared to adhere as closely as possible to the proprieties of high society. During the trek to Base Camp, a young Sherpa named Pemba rolled up her sleeping bag every morning and packed her rucksack for her. When she reached the foot of Everest with the rest of Fischer's group in early April, her Pile of luggage included stacks of press clippings about herself to hand out to the other denizens of Base Camp. Within a few days Sherpa runners began to arrive on a regular basis with packages for Pittman, shipped to Base Camp via DHL Worldwide Express; they included the latest issues of Vogue, Vanity Fair, People, Allure.

Having Pittman on the mountain is a source of amusement or entertainment at first:

The Sherpas were fascinated by the lingerie ads and thought the perfume scent-strips were a hoot.

Many of her teammates are nonplussed. Krakauer even says,

Scott Fischer's team was a congenial and cohesive group; most of Pittman's teammates took her idiosyncrasies in stride and seemed to have little trouble accepting her into their midst.

This would seem to support the thought that mountaineering creates bonds with fellow climbers. Yet, in the way that Krakauer describes her, the reader comes away with a sense that had it not been for Sandy Pittman, many other people could have been saved. She fatigues Lopsang with her trivial needs (he has to bring her a phone and he "short-roped" her to help her ascend). There is no sense that differences between people were erased on the mountain.

A reader can certainly go either way on this question, and I do think that there are examples from within those chapters that support and refute the quote. There a couple of things to keep in mind too. It is common for people to be friends through actions. This doesn't mean that they do things for each other. It means that a friendship can exist through common hobbies, activities, and so on. Let me use an anecdote from my own life. Every so often, I will go golfing with two or three friends of mine. My wife is always shocked to find out that I spent four hours with these guys, and I didn't learn anything new about their wives, children, or jobs. We talked about other stuff or didn't talk at all. Simply being together and doing the same activity was the friendship bond. This might make it seem like these types of friendships are shallow, but it does support the quote. The activity simplifies the relationship by forcing the group to smoothly operate the task rather than develop a deeper relationship.

The other thing to keep in mind is that most of the climbers on Everest during Krakauer's account were never great friends to begin with. Most of them meet each other for the first time on the mountain, and their only initial bond is the mountain itself. It is a challenge to be conquered, and the "friendships" exist simply because all of them are aiming for the same target and working together further helps them achieve that goal.

Chapters 11–15 are the chapters that show readers how things went from bad to worse in a hurry. Readers really begin to see an every-man-for-himself mentality once the summit is in sight and especially after obtaining the summit and seeing the weather begin to turn bad. Climbers that appeared to be friends begin arguing and leaving each other for dead on the mountain. Part of this is due to the human survival instinct taking over in combination with oxygen deprivation.

However, there are moments that show the opposite. Chapter 15 shows Boukreev making heroic efforts to save as many people as possible.

Krakauer himself is a good example of both sides of the quote. He is one of the climbers that helps fix the final ropes in order to speed along the process of the climb for himself and his friends, but we also see him make minimal effort to help other climbers on the way down. The friendship that was secured by the common goal and task begins to fall apart as that is either met or loses importance.