Synchronization does not offer benefits of proper back up.
Ransomware propagates through sync
How so?
If ransomware starts encrypting your files then the sync will just upload that encrypted data.
How is it different to upload a disk image containing encrypted data?
You can also use versionning when you sync your files.
Because i want to be able to restore latest working state as quickly as possible, which includes all configurations of all my apps without having to fix missing license keys in the windows registry, setup accounts, and other fiddly settings.
I do file backup of my photos, documents, invoices, and other random things I've setup for backup.