I suppose that we have a different view of injecting a bit of realism into a fantasy game. Following the flow of this debate, I would assume that this crowd thinks it's completely feasible that a Monk's unarmed attacks would not only affect opponents in full plate, but also creatures that may only be harmed by magical weapons.
Of course. This is D&D, not GURPS or something. You tossed realism out the window when you decided it made sense that, in the game-world, anyone can learn to just gibber out some words and twiddle their fingers and make sh%t blow up, or pray and make sh&t blow up X number of times per day, every day, because that's just how often their deity was willing to answer with blowing-sh&t-upness of that particular sort each day, no matter the circumstances, and that anyone with a sword and some combat experience can kill giants or trolls or dragons or chimeras while surviving their acid-breath or fire-breath or whatever, even if fighting nekkid. Or even just by accepting that absurd and physics-or-biology-defying things like giants, trolls, dragons, and chimeras could exist in the setting to begin with. Yes I'm aware that's a giant run-on sentence, it's intentional, it's supposed to be silly.
If random Joe number 1 can learn to gibber and make stuff blow up for no obvious reason, and random Joe number 2 can stab a 30-foot-tall giant a few times in the feet/legs and kill it without being crushed to death by the freakin' TREE it uses as a club, why the H-E-DOUBLE-HOCKEY-STICKS can't random Joe number 3 learn to break through a dragon's or knight's armor with his bare hand and crush the squishy meats inside? Or punch a ghost and actually hurt it because of his own enlightened spiritual development as a monk?
Not to mention that arbitrarily changing some rules for "realism" breaks the game, unless you change so many other ones to make it work alright again. For example, if you let rogues Sneak Attack anything that's even just mildly or moderately slowed down/hampered, you'd better as heck reduce their SA damage to 1 or 2 points per increment instead of 1d6. It's meant to be balanced out by how rarely you can make such a precise strike to the enemy's vitals. If you take away the rarity of use, you'd better as heck reduce it's damage, just like a fighter's Weapon Specialization is just +2 damage because he gets to apply it ALL THE TIME. Also, for example, if you decide that monks can't hurt guys in heavy armor or things like dragons that have heavy natural armor (which would include most of the Mosnter Manual, since a lot of critters have natural armor equal to or greater than heavy armors), you'd better let the monk flurry with any kind of melee weapon so he can actually participate in battles beyond 2nd or 3rd level.
And you'd have to overhaul the majority of D&D rules if you wanted realism. This is NOT a realistic game by its very nature. Hit points and Armor Class and a lot of other things will need to be replaced. May as well ditch your Monster Manual and most of the core classes, since hardly any of it is feasible in a "realistic" game with "realistic" laws of nature and science. Otherwise, rethink just how "realistic" monks and fighters and wizards and clerics and rogues and dragons and giants and stuff really need to be. It's only a game! Don't worry about realism!
But again, maybe I brought this upon myself by attempting to add any realism at all -- maybe the game & the rules as they stand should be left to people who enjoy flying around on magic carpets, or boots with wings on them, firing lightning or fire out of every orifice while their singing sword fights his adversaries all by itself. BTW, we don't even use the Monk character because of the unrealistic flavor of it in a medieval setting...(kiaaaaaa!!)
Try GURPS if you want serious realism in a game. Not D&D. D&D has always had things like hit points, armor class, magic-users, magic carpets, DRAGONS, and other patently unrealistic things. It's the whole POINT of the game!
And you don't have to be snarky about anyone
actually enjoying D&D for what it is and always has been. The rules have always been unrealistic and fantastical; that's the whole nature of D&D being D&D. You don't have to run D&D as high-magic, but you do have to accept that, if you're playing D&D, you're playing a game based around the fantastical and heroic, not the boring and mundane and hyper-realistic.
And since when has D&D been purely medieval in setting? Oriental Adventures and other settings had been put out during 1st Edition AD&D. I'm not even sure if, prior to that, OD&D might've had some non-European elements in it. Haven't Ogre Magi (a blatantly oriental monster, though using a western name equivalent) been around since before AD&D, or were they first introduced in the 1E AD&D MM? Hasn't D&D long drawn upon myths of demons and other monsters from other parts of the world than Europe since more or less the beginning? Sumerian and Babylonian demons and such? Not to even MENTION genies, djinn, sphynxes, ILLITHIDS (ia! ia! Cthulu ftaghn!) and stuff.
Or the crashed spaceships and rayguns and six-shooters and other things that have been there since the originaly D&D groups' early campaigns and some of the early published modules. Did you even PLAY 1st or 2nd Edition?
Seriously, you can't just deny that D&D hasn't had wierd or non-European elements "until recent editions." And yes, I'm aware that's a double-negative, it's just so silly to think D&D has been strictly "medieval European" since forever.
And how do you think martial arts has spread like it has in the real world? It started with probably Greek Pankration being spread to the east, where it evolved into Shaolin Kung Fu and from there into other martial arts. Then later contact between east and west resulted in people learning martial arts and bringing those arts back to the west, founding schools and dojos of their own. In a D&D setting, who's to say no Shaolin-style monk or western trainee never bothered traveling west and teaching their philosophy and martial art to others?
Unless you're playing a strictly historical campaign, in which case, why use D&D and its magic-users and dragons and junk at all?