A good hitter can hit with any barrell. ALL others benefit from the larger hitting area if the bat is within the right "wndow" for length and weight for the kid.
Period, end of story.
And many of the better hitters prefer the bigger barrel as well. Do big leaguers hit with the "pea shooters" guys like Tony Gwynn used to use? an't remember the model numbers... P271's? 241's?
A buddy of mine used to work for the AAA Indianapolis Indians, and I have about a dozen broken bats. He has 100+. How many are the little barrells... or the equivalent of a 2 1/4 inch for a kid in 5th grade or older?
Very, very few. I have a Tom Foley bat, which has "National League" smudges and imprints all over it from foul balls, and it is a toothpick. I've hit infield with it at my son's fall ball league before (7th, 8th, 9th graders) and it is immediately the smallest bat at the park the moment I show up.
"Herman Franks to Sal Yvars to Bobby Thomson. Ralph Branca to Bobby Thomson to Helen Rita... cue Russ Hodges."