How do you know how often those files need to be backed up without reading them? Timestamps and sizes are not reliable, only content hashes. How do you get a content hash? You read the file.
If timestamps aren’t reliable, you fall way outside the user that can trust a third party backup provider. Name a time when modification timestamp fails but a cloud provider will catch the need to download the file.
If timestamps aren’t reliable, you fall way outside the user that can trust a third party backup provider. Name a time when modification timestamp fails but a cloud provider will catch the need to download the file.