What's the (Hit) Point?

Aren't Hit Points, Armor Class, and Saving Throws all measures of the same thing in the mechanics of classic era dungeon exploration games and their contemporary offspring?

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Continuing for just a bit on my theme of minimalism (inspired by my upcoming sessions of Dagger for Kids with middle school students), cutting ability scores out of the game left me wondering about what else could (or should) go while still preserving the essence of the game.

When explaining hit points to tabletop newbies (quite a few kids already know the term from console and online gaming) I generally tell students, "It's your health.  It tells you how much damage you can take before your character is killed."  This is right in line with how we played back in the 80s and matches how Tom Moldvay explains things in Basic D&D: "Hit points represent the number of "points" of damage a character or monster can take during battle before dying.  Any creature reduced to 0 hit points (or less) is dead" (Moldvay Pg. B6).

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J. Eric Holmes's earlier discussion in his own beginners book is more terse, but covers the same ground. After telling us how to roll for hit points, he explains, "This represents the amount of damage the character can take ... If his hit score falls to zero he is dead." (Holmes Pg.7).

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The outlier is the 1979 Advanced Dungeons & Dragons Dungeon Masters Guide (no apostrophe).  In it, Gary Gygax insists that it is "unreasonable" and "preposterous" to interpret the gains in hit points made as a character increases in level merely as an increased ability to sustain physical injury, insisting instead that a proportion of hit points reflect increased skill in combat, sixth sense, sheer luck, and "the fantastic provisions of magical protections."  He manages to express the same idea somewhat more succinctly (and this time without any reference to Grigori Rasputin) in the AD&D Players Handbook.

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Okay, fine.  So if we harken to the creator of the game, we accept that only part of a character's hit point total represent "meat", then the remainder are essentially his or her ability to get out of the way of danger.  Got it.  But what about armor class?

  

Armor class, in role-playing, is inherited from the Chainmail Rules for Medieval Miniatures (1975) and wargaming practice and rules going back into the foggy depths of time.

At the most basic, armor class reflects a unit's (or character's) ability to escape harm, mainly through the use of protective equipment.  Dexterity modifiers to armor class muddle this somewhat, because they are obviously indicating that armor class can also be reflective of a character's ability (or inability) to avoid injury by getting out of the way.

How about saving throws? (You can see where this is going, right?)

Here's a link to more than you probably want to know about the history of saving throws.

Whether you break them down into five categories as in AD&D, or three as in 3rd Edition and Dungeon Crawl Classics, or a single category as in Swords & Wizardry, we see again that saving throws are a measure of a character's ability to evade or, at the worst, endure sources of harm.

Question: So why are there three separate mechanics to tell us if a character escapes harm or not?  

Question:  Within any one of those three sub-systems, what is the purpose (if any) to the level of granularity represented?

  

Why aren't Dexterity bonuses added to hit points (evasion) vs armor class?

Why are there saves against breath weapons and ghoul-paralysis, but not against falling or the acidic touch of some oozes?

If we accept Gary's conceit that hit points are both physical and metaphysical, would the game change significantly if we just dumped saving throws completely?

How might that work?

• Death Ray / Poison: drop save or die and let them do 2d6 to 10D6 damage depending on potency
• Magic Wands: each wand gets assigned its own Hit Dice, rolled whenever a charge is expended in an attack. If the total rolled exceeds the (healthy) total of the victim's hit points then the harm is done, if not then the effect is successfully resisted. E.g. a 3 HD Wand of Illumination allows the wielder to throw 3D6 with each charge and will almost always be able to blind a goblin, but will seldom work on an ogre.
• Paralysis or Turn to Stone: Roll XD6 when the attack is made, where X = the hit dice of the monster.  As with wands, if the total rolled exceeds the (healthy) hit point total of the victim then the effect takes hold, otherwise it is resisted and no harm is done.
• Dragon Breath: Save for half damage is gone.  Roll XD6 for damage where X = the hit dice of the monster
• Rods, Staves, or Spells work as with magic wands. This also allows spells to scale up easily.  A 10th level magic user's Charm Person spell becomes much more fierce than that of a level one newbie.

Could similar changes likewise fold armor class into hit points?  Maybe a suit of plate and mail adds 20 hit points to the wearer or an ablative effect so that the first 10 points of any blow are absorbed.

Could a single-stat game maintain the spirit of classic editions of D&D and other fantasy-genre games sufficiently to preserve the feel of those styles of play without the complexity, or is complexity itself a goal of the game?