In fairness, most of Ruger's rifles were known for spotty accuracy until the early 1990's - then they started hammer-forging their own barrels, and the accuracy of all their rifles improved thereafter. In particular the Minis got heavier barrels, too, at some point in their production, but I forget when. They also started using rubber buttplates at some point, which stay in one spot on your shoulder, which also helps.
I can't think of any thing a Mini can do, that an AR can't do as well. But there are a few things an AR can do, which the Mini also does well - like say fire five rounds at a running yote.
