Why Was It Considered Impossible Back Then Even Though It Can Be Done Now?

Once deemed impossible to scale Mount Everest without an oxygen mask, this belief endured until the late 1970s.

However, Reinhold Messner and Peter Habeler defied this notion in 1978, accomplishing the unprecedented feat of ascending Mount Everest without supplemental oxygen. Their success was the culmination of rigorous training to acclimate to the high-altitude, oxygen-deprived conditions of alpine environments.

Since then, over 150 climbers globally have conquered Everest’s towering summit, exceeding 8,000 meters, forsaking the use of oxygen apparatus. Why was it considered impossible back then even though it can be done now?