That's only one approach, Drop. Another way is to open up their centerline, giving you access to vital striking points, i.e. eyes, point of nose, chin, throat, sternum & plexus, low-center gut, groin all of which are prime things to put a fist into and which are generally accessible if you are successful getting to the rear and/or flank.
Granted, there's lots of stuff to put a fist into on the rear/flank, too. Just pointing out that the conclusory statement that you made above isn't the be-all, end-all of fight tactics. I personally do it that way myself, following a "close 'em up to soften 'em up, then open 'em up to finish 'em" method....