Well, for rat-a-tat or pew-pew-pew you might be right.
"This is the AK-47 assault rifle, the preferred weapon of your enemy, and it makes a distinctive sound when fired at you, so remember it. It ain't in any of the history books. Just a little piece of war. Hell, the place didn't even have a name; just a number." Gunny Highway
However, for versatility ye be wrong.
AR uppers have a variety of options...Like a long range 24" triangle barrel upper, short tactical upper, 300 BLK upper, 22ARC upper these come to mind for some reason...
I mean its kind of like going to the prom with a husky Russian woman named Helga and dancing with her all night or going to Fort Lauderdale and parting with bikini clad American girls...