The most critical flaw in the your logic is ignoring identity-level compromise. If Microsoft's automated algorithms flag your account for suspicious activity, or if your credentials are stolen, access to all cloud backups is instantly severed. You cannot roll back a OneDrive account you cannot log into.
Live-sync cloud storage is a two-way street. If your local machine is hit by a modern ransomware strain, the sync engine will immediately push those newly encrypted, corrupted files up to the cloud. While OneDrive does have a rollback feature, advanced threat actors know this; they routinely target your Microsoft 365 identity first, using stolen credentials or session tokens to purge your cloud version history before they ever drop the encryption payload on your local machine.
This is exactly why cybersecurity frameworks and government agencies like CISA now strongly recommend the 3-2-1-1-0 backup rule rather than the outdated baseline models. This modern standard mandates keeping three copies of your data across two different media types, with one offsite, and crucially, one that is either immutable or completely 'air-gapped.' An air-gapped backup is an external hard drive that is physically unplugged and sitting in a drawer. It has an attack surface of absolute zero. A hacker on the other side of the globe cannot encrypt a piece of hardware that has no physical connection to a network or a power source. Relying exclusively on the cloud is a gamble on normalcy; true data resilience requires physical isolation.