Good effort, but wouldn't it be better if such backups were split into n parts and distributed among n independent providers using something like shamir secret

Good effort, but wouldn't it be better if such backups were split into n parts and distributed among n independent providers using something like shamir secret sharing where a backup could then be restored with k out of n parts? I trust Signal but I find this quite basic compared to just how much thought/work went into the Signal protocol comparatively.