The pure difficulty of the technical climbing was not remarkable.
The grade they gave was M7, AI5, A0. M7 is moderate, AI5 is moderate but strenuous, and A0 is the very easiest A grade. The details of what these grades mean are discussed in other comments. If there was a climb with that grade close to the road in the U.S. Rocky Mountains, it would be considered a fun but not-too-challenging day of climbing by these guys.
But combine this moderate climbing grade with: the weight of a week's worth of camping supplies; the very high altitude; the very cold temperatures; the constant threat of terrible weather; the constant threat of avalanche or ice fall; and the very far distance from any kind of help... and you begin to see how it is a remarkable achievement.
The risk of death was high, yes. But it's not like playing Russian Roulette or running across a busy highway or something. The hazards are inherently part of the climbing goal, and a huge part of the achievement is in how the risks were mitigated: peak physical fitness; long climbing experience; the lightest gear; the best weather forecasting; the best planning and logistics, etc.
Metaphorically: you can't build a plane with the same safety margins you use to a build a bridge. And you can't get a rocket to orbit with the same safety margins you use for a passenger plane. The harder the objective (physically), the smaller the safety margin is available, and the more skill and expertise it takes to make it work.
The grade they gave was M7, AI5, A0. M7 is moderate, AI5 is moderate but strenuous, and A0 is the very easiest A grade. The details of what these grades mean are discussed in other comments. If there was a climb with that grade close to the road in the U.S. Rocky Mountains, it would be considered a fun but not-too-challenging day of climbing by these guys.
But combine this moderate climbing grade with: the weight of a week's worth of camping supplies; the very high altitude; the very cold temperatures; the constant threat of terrible weather; the constant threat of avalanche or ice fall; and the very far distance from any kind of help... and you begin to see how it is a remarkable achievement.
The risk of death was high, yes. But it's not like playing Russian Roulette or running across a busy highway or something. The hazards are inherently part of the climbing goal, and a huge part of the achievement is in how the risks were mitigated: peak physical fitness; long climbing experience; the lightest gear; the best weather forecasting; the best planning and logistics, etc.
Metaphorically: you can't build a plane with the same safety margins you use to a build a bridge. And you can't get a rocket to orbit with the same safety margins you use for a passenger plane. The harder the objective (physically), the smaller the safety margin is available, and the more skill and expertise it takes to make it work.