Backblaze has explicitly said more or less the exact reason they don't have a Linux client for their one-price-fits-all backup service is that they don't want people backing up multi-TB NAS devices. The folks over r/DataHoarder/ would absolutely destroy them if they offered unlimited backups for NAS devices for $6/month - many of them have hundreds of TB on their personal NAS'.
Its absolutely the correct business decision, and as you note, you are more than welcome to use B2 and pay per GB for as much storage as you want.
Its absolutely the correct business decision, and as you note, you are more than welcome to use B2 and pay per GB for as much storage as you want.