Well that’s not wrong.

Close, but imprecise. I’m saying two things:

You can lose data with a faulty hard drive if your backup is silently corrupted and you don’t realize it. That’s not a risk here, as long as before restoring from backup you upgrade the phone OS to patch the bug.

Also, you can lose data with a faulty hard drive if you have no backup.

Rooters especially will care about these points since they typically cannot restore from backups without upgrading the phone away from a rooted version, due to choices made by Apple in firmware.

Actually, if an iCloud erase works, it should be possible for Jailbreakers to recover their phones without updating.

Mind, they will still loose data, including some Jailbreak stuff that isn't included in iTunes backups.