There are a number of ways that people get remembered, be it through funerals, quilts, or even statuary. All of this is part of the process of grieving, and is a way that the living say farewell to the dead; it is part of the how we remember the fallen. For a lot of people prayer is also part of how they say farewell, but not everyone is sure what needs to be said. Because of this they look for those that have experience in saying a memorial prayer, especially if they are looking for ways to make sure that the prayer is heard. As there are few experts in such a prayer, they look for those that pray the most.
This is part of the reason that cenacle prayers are seen as the solution to so many different issues. Stereotypically a group of older women that gather in a room in a church that gather to deal with prayer requests, they are often the ones asked to deal with a memorial prayer; they have the most experience praying, and that experience is valuable during such an emotional time. The family of the person being memorialized wants to make sure that the prayer is done right, and this is something that is seen as possibly the last time that anyone will focus on the person in question so it is important to do right.
Ultimately the memorial prayer is something that must be done right. While people are more than willing to merely ask others to do it who they know can be trusted to do it, they need the assurance that it will be done. The final prayer is the one that allows them to let go, and that makes it the most important prayer that will ever be said about the person. As such it is helps to know someone who can do it right, and that can be a cenacle circle that the person respects. You can get more info about it on this site.