I keep backups (regular, incremental, remote) to keep my data safe in case something happens to my local data. This protects me from things like theft, hardware failure, accidental deletion of some important files. Having multiple generations (daily, weekly, monthly) will protect me when I delete some files and only realize weeks later.
All of this is a separated issue to having encryption or not. I encrypt both local and backup copies, and store the keys in a password manager.
See what works for you, but don’t confuse the issues.
Don’t.
Everybody hates preachers.
Lead by example.