I've used "Scout" scopes for 15 years on a number of rifles...there are several advantages- a load of non-critical eye relief and freeing up space over the action (which can be significant on a bolt gun), you also won't frost the ocular with your breath on winter hunts up here.
I can shoot with both eyes open on the 2.5x and have dropped game out to 275yds. so I never understood the utility of the newish 1.5-5x IER.
The biggest advantage to me is speed- it is just a very fast type of sight to use.
Don't overlook a real disadvantage- when the sun hits the ocular over your shoulder it can wash out the image unlike a conventional scope that will be shaded by your head.