The way I read that issue and the linked discussion was, that pgBackRest handles a lot of details itself that's otherwise handled by Kubernetes. Hence, a lot of functionality in pgBackRest is not only redundant but incompatible with how Kubernetes CSI could be used to provide incremental and differential backups. Hence, Barman and `barman-cloud` plugins are a better, natural fit for a Kubernetes environment than pgBackRest.