No, someone had made a comment about working the midback wthout involving the biceps and I simply pointed out that it's not possible unless you don't bend the arms.
Hence the shrug-back.
It can make a good secondary back exercise (for example, if your bis are trashed from heavy pulldowns or chins and that's going to limit your midback work) or as a way to continue exhausting the midback after your arms fail in a set.
So a back workout might be
chins: 4 sets of 6-8
Now that the biceps are tired, doing full rows is probably a losing proposition, arms will limit what you can do to your midback. So you do
Shrugbacks: 3-4 sets of 10-12
then traps, low back, etc.
On a different back day, you could do full rows as your first back exercise and follow it up with lat shrugdowns (same movement, shrugging down instead of back) or pullovers or some other lat exercise taht doesn't involve the biceps.
Because of the amount of weight most people cna use on shrug backs or shrug downs, machines are generally a better idea (or hang weights off a belt and do chins but only shrugging your body up). My old training partner, who was a strong motherfucker, was able to max the Hammer Iso Row machine out (5-6 45 lb plates per side) on shrugbacks. Trying to do that with a bent over row would have killed his back.
Lyle