The memories are not real people.
They're AI chatbots using your grandma's voice recordings.
And they require the power of souls from actual living people to power these AI chatbots.

Which, are not even used by the actual living people. Because somehow there is no hypocrisy in deleting someone's memories from your brain once they die. Even in this culture of "you don't truly die unless you're no longer remembered"?

"questionable ethics", yeah right.
Will you be the first to sacrifice yourself so someone else can listen to an AI interpretation of their dead grandma?

If they had this culture, this system, but it was stable and self-sustaining without the need to endlessly consume souls of the living to power this system, it would just be another culture. It's weird, but they can do whatever, it doesn't affect people outside of that culture.
... but the moment that they required the souls of the living and had to kill the living people from outside of their culture, and we had to make a hard call between the memories or the actual alive people across all shards + Source... is when they lost all sympathy and had to go.