Incidentally, that first post is an excerpt from Alexis' "Masterclass" on DM'ing, available to his patrons on Patreon (of which I am one). I can highly recommend it. Alexis analyzes the DMing techniques he has used in his online campaigns in detail, outlining his thought process, what he was trying to do, what worked and what didn't, and generally giving a fascinating look inside the mind of someone who has run more D&D and thought more about the game than probably anyone around.
Alexis is uniquely suited to running a class like this, having DMed for decades, being one of the most considered thinkers on the game (as demonstrated by his long-running blog and several thoughtful books), and by virtue of having two fairly long-running campaigns run on line using Blogger (and which are therefore preserved in their entirety, and available for extensive analysis and discussion).
You should go sign up! Anyway, back to our regularly scheduled programming. I promise I'm not being paid to say that, haha!
Weapons on the Defensive - not in D&D!
Alexis was making the case that the weapon's role in your defense is already accounted for in the system.
There's only one problem with that idea - dropping your weapon does not change your opponent's chance to hit you whatsoever.
Which I would say is proof-positive that the weapon's defensive role is not, in any way, included in the system. Increasing defensive prowess with level is included (as represented by increasing HP per level). The weapon's role is decidedly not.
Increasing Defensive Skill and Hit PointsAs Alexis points out, D&D uses increasing hit points to model increasing defensive ability with level, but not quite in the way Alexis described (at least not in its original incarnation, which I would argue is still the metaphor used in the game today, despite its origins being lost in time).
In Chainmail, one hit was one kill. In OD&D, *on average* one hit was one kill, but they made HP and damage both 1d6 to add a little randomness. The idea was still the Chainmail conceit that one hit killed a normal person. The Chainmail "hero" took 4 hits to kill, essentially giving the hero 3 mulligans on death, and that's the same approach that OD&D took - each additional hit die *on average* is one mulligan against death. A "hit" was always supposed to be a lethal, fight-ending blow. This neatly explains why characters fight at 100% until they're dead. The waters were muddied as time went on and hit dice and weapons started being different dice, but if you clear away the murk, that is the foundation of the current system.
The Issues with Defense in D&DIn analyzing the issues with defense in D&D combat, we need to tease out and treat individually each of the three factors to defense: hard-to-hit, hard-to-hurt, and hard-to-kill. D&D rolls hard-to-hit and hard-to-hurt into one stat (AC), but also puts some of the hard-to-hit into the hit point. It ignores the role of the weapon in hard-to-hit, despite being (possibly) the most important factor. The hit point then involves some hard-to-hit and some hard-to-kill. It's all very muddled.
This muddling causes a variety of issues. For just one, a giant-thrown boulder falling on you doesn't care one whit about your defensive abilities or your armour. It just does damage, and will do damage to Lancelot or his squire equally. But because defensive abilities and life force are rolled into your hit points, and because armour and dexterity are rolled into your hard-to-hit, it's difficult or impossible to tease out how to apply damage in a scenario like that. Theoretically, it would be something like having the giant roll against "touch AC" (which I think only existed as of 3e, being your armour class not counting your armour) and then roll damage multiplied by level (to remove the effect of increasing defensive ability being rolled into the hit points).
Also, because damage doesn't scale up with level, it means that two high-level characters who are equally matched will take a long time to finish a fight, whereas two low-level characters who are equally matched will finish quickly. Which doesn't pass the smell test to me.
Healing is difficult to reconcile into this system, because ostensibly some of your hit points are meat and blood, and some of them are fatigue, and some of them are your increased defensive ability. Well, which ones does a cure spell work on? Which ones get whittled away by walking hours in the cold? It's unclear, because the HP is a mixed metaphor from the get-go.
SolutionsYou can actually fix all this pretty easily in D&D combat by making the following changes.
Hard-to-hitWeapons and level influence hard-to-hit (i.e. your "AC" is set by a level modifier and a per-weapon modifier). One should actually have three hard-to-hit stats - dodge, block, and parry. Dodge is used against the giant's boulder, a ballista bolt, dragon breath, etc - anything that can't be blocked or parried. Block is used against normal missile attacks and includes the shield. Parry is used against normal melee attacks, and includes the weapon's defensive bonus.
Hard-to-hurtArmour influences hard-to-hurt (i.e. it reduces incoming hit point damage).
Hard-to-killAnd hit points represent only hard-to-kill (i.e. just meat and blood - all hit point loss is of a constant magnitude). This integrates naturally with Alexis' hit points for mass system.
ConclusionReally, the only difference mechanically from D&D combat is including damage reduction, which is easy enough and better matches our intuitive understanding of what armour does anyway. D&D needs the three categories of hard-to-hit, it just ignores the difference (to its detriment), and it's easy enough to add these to the character sheet.
I don't think any of this is better just because it's more "realistic" (although it is). It's better because it makes each stat clearly model something understandable. This makes it intuitive, easy to understand, and easy to apply to edge cases that weren't necessarily envisioned by the designer. Because the model is explicit and understandable, it's easy for the user to tinker with it, and easy for the DM to make rulings on the fly.