i think that's it. We used to use CD-Rs and DVD-Rs to record playlists and movies, respectively. Data hoarders today will prefer multi-hard drive servers over burning everything to Bluray, and for one-time file transfers, we have flash drives and online file shares. I just can't think of a use case for BR-R that isn't better served by a different technology.
Presumably when we're talking off-site backups we're talking about a separate company sitting somewhere in an abandoned nuclear bunker which can justify the price of a tape drive or twenty.
When the tape drive fails and eats your tape in the process, you better hope you have a second backup or you'll be crying salty salty tears.
I worked in the service center for a tape-drive manufacturer and I would routinely see the drives we got back for repair. They were often taken apart by the customer in a frantic and desperate attempt to get their cassette out. The cassette was almost always still in there though, with multiple feet of tape snagged and wound around everything.