Because both of them are somewhat mature emotionally and intellectually. Anakin, knows what is fear, what is anxiety, what is life and death. Anakin, even knows what love is, and above all, all his thoughts and nostalgia are directed to his mother. So much emotion, so much thought, it was not strange for someone to take Anakin’s place, but not like a Jedi at all. The Jedi were taught to suppress all emotions, all private emotions, in order to focus on the divine power. And after all, it is easier to teach a 4-year-old child not to be afraid of death, to suppress emotions, than to teach a 9-year-old child, because 9 years old, to be able to be aware of all things. That’s it … Anakin is too old to start training, too much emotion to be a Jedi …
Seen more at: Darth Vader use the force poster
