I don’t agree with the idealized view many people have of Qui-Gon. While it’s true he was more open-minded, understanding and willing to listen than the Jedi Council, he was still a fairly orthodox Jedi who followed all the rules of the Order. In my opinion, he might have delayed Anakin’s fall, but he wouldn’t have been able to prevent it entirely.
Isn’t that the point of the Xanatos character in Legends?