I use rar for backups as well. Its superpower is recovery records. Reading bytes off a hard disk doesn't always work the same years later. I have seen corruption on hdds.

Also use it to span backups across multiple archival M-Disc blurays.

I also prefer the UI and configurable dictionary size to 7zip. Rar lets you isolate each file if you wish instead of solid compression. Ever had to insert 2 blurays just to get a 3kb text file out of an archive?