This paraphrase of jggimi's statement out of context is misleading. It takes a careful reading of this tutorial, I think, as well as some interpretation or inference of the intended meaning, to avoid walking away with the impression that rsync used alone (even without one of the --delete arguments) will delete files in the destination directory and that rsnapshot is
the (as opposed to
a) solution to that.
I believe it doesn't intend to say that at all. Your first phrasing is clear enough in only saying rsync --delete falls into jggimi's case of backing up your deletions: "The rsync '--delete' option makes this script unsuitable for backing up purposes." Then to me it would be clearer to follow up in your next tutorial with a modification of this script with different rsync options that make it a backup script rather than only a mirroring script (no --delete, but with --link-dest?) rather than proceeding immediately to an rsnapshot tutorial.
Myself, I don't want to go to rsnapshot but like to code my back up scripts myself. This lets me do something a little weird: I have a small disk laptop that I snapshot to an old Macintosh with a larger harddrive and some older files that never fit on the laptop. After I rsync from laptop to a subdirectory on the powermac I rsync from the powermac the full set of files minus some exclusions to a USB drive. Not sure this will fit into someone else's idea of a backup or snapshotting program. Then writing it myself also helps me to remember better what my "back up" (I'm still foggy on the rigorous definition of a back up -- sysadmins seem to have a stronger definition than I do) does exactly.
I like this phrasing of jggimi's too, but have to admit I've had occasion to want to backup some of my deletions, not to mention my moves. First, there are some things you genuinely do not want to exist anywhere. Second, in my half baked "backup" schemes I sometimes run out of space on the back up media. Yes, I suppose disks are cheap but not necessarily
cheap enough for my taste. My back up space is sufficient again now, but I expect whenever I get around to using --link-dest in my script this may change eventually. Hmmm, I wonder how --link-dest and --delete interact, if at all. Maybe I will only have to delete selective big, old, no longer extant on the source drive files directly off the back up medium manually. Maybe you could argue that's a safer bet than rsync --delete in the first place.