Arguably the most distinguishing benefit is transparent en-/decryption of the contents of your sync-set, such that the cloud copy is always encrypted by your key that's only available at your endpoints --- this is unrelated to being encrypted with a vendor-controlled key.

EDIT: Also, most 'official' cloud drive clients place a folder into your homedir, like ~/Google Drive or ~/OneDrive or ~/Box Sync. Only files placed into these folders get synced up and down. This client allows arbitrary local paths to be synced up or down.