"It takes a huge effort to free yourself from memory."- - - Paulo Coelho
People are often filled with regrets. Regrets are the lingering pain from experience. A bad break-up can haunt a person for years. The memories and "what I did wrong" without answers can led to life long fears and depression. It takes a conscious effort to erase the past in order to move on into the future.
Some LOST characters were paralyzed by their pasts. Many were haunted by abandonment issues. Many were haunted by "daddy" or parent issues. Many believed they were abused. Many believed that they were chosen by fate to have lousy lives. Many believed they were be punished for no apparent reason.
Many characters wanted to escape their present circumstances. Many dreamed of grand adventures. Many believed that they had godlike skills. Many thought they could turn back the clock and change their past.
But in the end, none of them could change their pasts. The only thing they could do was to wake up and acknowledge their past life . . . and accept it. Accept the consequences of their own actions. Release their regrets and anger against others. To purge themselves of guilt. Free themselves of their own self-pity.
Otherwise, they will continue to rot from the inside to become soul less loners who would contribute nothing to society. They would be crippled by their own memories of a past that was re-written to make them more and more the victim. Victimization can lead to withdrawal and paranoia. It can lead to anti-social behavior. It can lead to a life of perpetual misery.
That is why so many people rely on therapists to help them through their issues. They need to talk their way out of their plight. They need someone to throw them a life preserver. They need someone who believes in them.
LOST's island life was not the true life preserver for the main characters. It was more an amplifier of their fears, anxieties, emotional darkness and loss of life. The island experiences did not set the characters "free" of their memories. No, it reinforced them in a negative way. In some people, like Ben, it emboldened them to act in a more negative manner. Their internal monster's thoughts became a raging real life monster. That is not personal growth but personal destruction because they could not free themselves of the negative memories of their past.
You need to realize that the past is hurting you in the present in order to stop painful memories from stopping you from becoming a better person. We don't think any of the main characters got past their past when they reunited in the church. It seemed like an awkward 25th year high school reunion of long lost strangers than a pivotal change in their lives.