I assume it’s not strictly necessary to download it. Most people are running a single cloud instance, who may or may not have a backup S3 bucket. Downloading the backup would be the only way for this group to make an off-site backup, like you mentioned.
I would even go as far as to make an additional backup system on a completely different provider as well, especially after what recently happened to this open source dev. Regardless of its validity, it’s a great warning to have a weekly or monthly backup to an entirely separate storage location/provider.