If they're in frequent/near-constant use, yes. As a "connect - back up - disconnect" device, they're decently reliable.
But other than that, you're absolutely right. Backups are the only thing that can prevent data loss.
OP: Having more drives lowers the chance of losing all your data in case of a single drive failure, but increases the chance of having a drive failure at all (more parts = more parts that can fail). If you're considering spending the money for a 1TB SSD, I'd spring the slight extra expense for a 2-3TB backup drive as well. Save a OS drive image to it and set Windows to use it as a file history drive. You'd still have plenty of space left for media storage or other space-consuming uses where the speed of an SSD isn't necessary.