AC is a reasonable abstraction for the combination of hitting the target and penetrating the armor. Some editions even had touch AC for situations where penetrating the armor was unnecessary.
The real nonsensical part of the D&D system is hit points. Someone hits you in the face, and you take "damage" and lose hit points. As long as you have some HP left, this "damage" is completely harmless and does not affect your ability to fight. If you are a high-level character, you can be punched in the face many times with no adverse consequences. Until you reach 0 HP, which suddenly makes you unable to take any action.
I remember hearing that the AC/HP system was originally borrowed from some miniature wargame involving ironclad warships. It definitely makes more sense in that context than with living creatures.
Also, if I remember correctly, the class/level system was the part of D&D that was considered obsolete in the 90s. Back then, almost everyone was using a system where you developed each skill and ability independently. Then 3e resurrected D&D and classes and levels became popular again.
The real nonsensical part of the D&D system is hit points. Someone hits you in the face, and you take "damage" and lose hit points. As long as you have some HP left, this "damage" is completely harmless and does not affect your ability to fight. If you are a high-level character, you can be punched in the face many times with no adverse consequences. Until you reach 0 HP, which suddenly makes you unable to take any action.
I remember hearing that the AC/HP system was originally borrowed from some miniature wargame involving ironclad warships. It definitely makes more sense in that context than with living creatures.
Also, if I remember correctly, the class/level system was the part of D&D that was considered obsolete in the 90s. Back then, almost everyone was using a system where you developed each skill and ability independently. Then 3e resurrected D&D and classes and levels became popular again.