Just a quick search about PM in 1998. Just saying PMs arm strength was questioned during the process, rightly or wrongly, by media pundits creating a "popular belief" that gets shot down.
All the panelists except Shanahan and Toledo, both of whom did extensive analyses of their own videos of Manning and Leaf before being interviewed, watched SI-provided game tapes. The group shot down the popular belief that Manning can't throw the deep ball. Indeed, the experts extolled Manning for making every throw with precision.
here is from your article on Manning
And on Luck, does not have top level arm strength. Again, not top level arm strength is not the same as inadequate arm strength.
Lastly, thanks for posting the articles.