Thanks for the reference. This is a useful guide to what "normal proportions" look like. My wingspan is 5'10". I'm 5'7.5". This is one piece of evidence which is pushing me towards not lengthening any more than 2.5" total.
I also find I look too lanky when I stand in lifts higher than that. Bone structure is not "thick" enough for the height. Don't want to be come Slenderman. Or T-Rex Slenderman for that matter.
If you are thicker boned/built like KiloKahn for example I think you might be able to push this a bit farther than someone like me. But like most proportion talk, that's just my opinion.
Key figure from the article:
In short, for 90% of men, arm span was between 2 cm and 16.53 cm greater than height. No one out of 287 men was taller than their arm span. Only one man was equal in arm span to his height.
Honestly though I don't think this should really discourage anyone from LL. What would you rather have? Short arms? Or short stature? In an ideal world we wouldn't have to choose. But personally, I'd rather short arms.