How far do you agree that Stalin’s position as General Secretary was the main factor in his emergence as leader of Russia?

I agree that Stalin’s position as general secretary helped him gain power but on the other hand there were reasons and mistakes made by the opposition such as Trotsky or Bukharin which helped Stalin emerge as a leader of Russia.
Stalin’s position as a general secretary helped him to gain power of Russia’s leadership, as he had a lot of the control of the party’s decision making. This means that he had the power of what was debated in the party’s conferences, he also had the power to advance the careers of those within the party and without his decision no one else could be promoted to different positions. He used his power to get people to be a Communist Party Member and promote them to positions such as the Party Congress, while manipulating this position to gain great loyalty from those who he was responsible for.
Stalin also was responsible for Lenin’s funeral, in which Trotsky did not turn up for because Stalin tricked him as he changed the date on which it was happening. This severely damaged Trotsky’s reputation and political prestige. On the other hand this helped Stalin as he made the most of the funeral to set himself up as Lenin’s disciple and who would carry on his work, this let Stalin’s reputation grow and Trotsky, who was seen as the person to take the leadership reputation, fall.
On the other hand Krupskaya gave Lenin’s testament to