Yes that's correct. The barcode is just your Skmiles number - so if your bag is recovered by a Delta agent they will scan and be able to see your itineraries, and contact info. So imagine the case that you're in ATL, they can quickly get an announcement going or intersect you at your gate. I've seen this happen before.

If it's recovered by someone else, the thought is that they will take it to Delta (since it's a Delta tag) and do the same.

Most people I know put a second form of ID on the inside in an obvious place, usually a business card. For my entire family I just made some business cards at home with specific contact instructions "If this bag is lost please contact in this order....".