Nice writeup. I don't think this is the "best" example though. The best example is Rangers dual wielding IMO. Rangers in 1E could dual wield the same as any other character (an offhand dagger or hand axe only and applying a penalty to both based on dexterity).More importantly, it is, perhaps, the best example I can think of where a rule that was widely misapplied, eventually became the default rule. And the default rule became popular, and continued to be used throughout editions, eventually becoming the modern 5e version (death saves, etc.)
Then along came Drizzt who was a Drow Ranger that dual wielded scimitars. Drizzt was able to dual wield because he was a Drow, not because he was a Ranger. All Drow dual wield as noted in the Fiend Folio. Because of Drizzt though, people started associating this with Rangers and it "became the default rule", changing only now with 5E.