length v girth? , NO, suppressors!

Being that a shorter platform is a selling point, is there a reason why I don't see fatter mods, I can understand too Fat may lead to it being in the way of the line of sight, but we have 2" donnie's in 6" and 10", why no 4". And why not a 3"x 3" using an off set adaptor, this could hang the Mod low and overcome the "line to sight" problem.

Is there a scientific reason why is would not work.
 
I 3D printed several moderators and found longer moderators were more effective than shorter fat ones. Also, there wasn't a significant difference in two equal length moderators of different girths. My conclusion: Longer is better than thicker. All my testing was done 30 FPE or less so that might not hold up as well with more air flow in higher powered guns.