Because I have encountered it, and others have, in more than one variation. In my time there are significant records pertaining to alternate histories.

To be redeemed is to make amends for what you have done. That is not returning lives that you have taken, nor contradicting any other event that was initiated. The warden decides when amends have been met, and that varies from individual to individual.

As for life after death... it is possible. Though mourning is not about the deceased, it is about what they have left behind. And I believe any individual would want their friends to care about them enough to miss their presence.