Well dents and scratches has nothing to do with outdoors, it can happen in office, home, indoors. So really you simply mean ruggedized. Personally I'd never buy it as rugged is just weight for a theoretical problem I'd rather carry a spare battery and place on on left one on right so a fall doesnt damage both.
If I'm heading into a physically hostile environment I've got a spare mobile in a waterproof bag wrapped in clothes in another waterproof bag, extremely difficult to then be out of action and that method weighs relatively nil and would be tougher than anything Anker could make. I usually in a hostile environment have my oldest less-worried-if-smallest mobile in my hand or easy access and the brand-new-would-cry-if-broke mobile cuddled deep in padding. I have for example a 4 year old Nexus 4 for that purpose still.
I speak with experience, I bought a rugged portable USB battery and its never left the house it was unboxed as its weight and volume I'd prefer to do without and I doubt it would survive that much of a drop, and I once bought a rugged mobile and its just a burden to hold. Just try holding rugged stuff vs non-rugged stuff in each hand.
I think Anker has hit the sweetspot of build quality for weight/volume.