For centuries a gedutu would always replace lost bits and pieces of the wielder. But it was only in the last 50 years that it would completely replace a wielder instead of seeking another. It was and still is a controversial process. But it was considered imperative to winning the war. If a wielder died and the gedutu went to find someone else who was compatible, then the effort could be down one more sapient. But if a replacement immediately sprung up in their place, then the effort could continue at full strength.
The process was much more lossy when it first started. Restored wielders were mostly the sum total of their knowledge and skills and little more. As things developed, the process was able to retain more and more parts of their personality. However, it's still not a complete and true restoration of the deceased. There's a certain something missing. And it's very easy to see why this doesn't go over well with many.
There's also an odd flaw where restored wielders are more susceptible to mind control. There hasn't been too much exploitation of that so far for various reasons. But it's only matter of time.