I assume you are asking about
rclone mount not just all of rclone.
iCloud “just works”
iCloud’s featureset is minimal, so just comparing extant features, I’d say it boils down to this:
It “intelligently” keeps local copies of things you use a lot, and offloads things you don’t. To open things, iCloud first needs to download the file to a local drive.
Rclone requires more user interaction and configuration. However once you get it set up, it also pretty much “just works” but nobody writes software that “just works” like Apple does...
Rclone doesn’t really have a facility to keep local files. It can cache files when opened/written to, but those are all ultimately pushed back to the cloud, and the local cache is cleared until the next access. It can also buffer/stream files for local use (I.e. downloads them in pieces and keeps that piece for the minimum amount of time necessary) which iCloud can not do.
There’s a long list of other features that Rclone supports (including encryption and multiple storage platforms) but those features don’t even overlap with iCloud so I think that’s beyond the scope of your question.
The other features you asked about are possible via command line only, and backups would need to occur at pre-set times instead of iCloud’s real-time offloading/uploading of changes.