According to this ted talk[1] he wasn’t. He led dangerously unprepared missions and ignored locals advice. Roald Admudsen was more successful and did it without the drama.
Only measuring leadership, as im the Ted x(!) talk, with achievement of a stated, and up to then impossible, goals and ignoring a leader who saves everyone from death is at best short sighted, at worst ignorant. Did I mention the guy in the talk is a business professor with a book on leadership?
Including the previously mentioned Nansen. Nansen was a generation earlier though, and among other things built the ship Amundsen used.
Amundsen made something difficult look easy. Everyone else made the difficult look - difficult. And survived.
Except for Scott who died.
There is an analogy there with software projects by the way, except for maybe the dying part replaced with general failure.