"a simple rsync job offers an actual offsite backup"
You don't understand what a back up is.
Hint: if it is not fully decoupled from the original source (as in "air gap") is not a backup. So an off-site rsync is not a backup; an off-site rsync and tarring the result from time to time to an external device, *may* be a backup.
You are probably in the league of those that think RAID5 is also a backup strategy ("sure, not always, not perfect, but in some simple cases...").
"Only recently has the 'malicious modification of files' rocketed to the top of the list"
The "my dog ate my homework aka I mistakenly deleted a file can you recover it?" has *always* been the number one cause of checking out a restore, closely followed by "damn! all our boxes are infected by a virus/our main server has BSOD'ed, let's reinstall and recover from backups" in windows-land. Ransomware is -alike those "evolution clocks", a 23:59:59 event.