That statement makes literally no sense. ADB still works just fine, so either you meant "and that is why I will be rooting my phones in the future", or this is absolutely not why you root your phones.
I think it's fairly obvious the poster meant that as in that kind of behavior, that takes power away from the user as opposed to exactly that particular reason.
ADB is also much less flexible. I have Titanium Backup making nightly backups, and then FolderSync automatically pushes them to a SFTP server I run. If something should happen to my phone, I'll lose one day of data. This is all automatic, so I don't have to think about it.
A backup like ADB that requires manual intervention is likely to be only done irregularly, and Murphy says that you'll lose your phone just after forgetting to make a backup for weeks.
Being able to do this is the only reason I bother to root my Android.