for the home user backing up their own data, I honestly think that raid has limited utility.
If I have 3 disks to devote to backup, I'd rather have 1 local copy and two remote copies, vs 1 local copy with RAID and 1 remote copy without.
If I have 3 disks to devote to backup, I'd rather have 1 local copy and two remote copies, vs 1 local copy with RAID and 1 remote copy without.
The third copy is in the cloud, write/append only. More work and bandwidth cost to restore, but it protects against malware or fire. So it's for a different (unlikely) scenario.