One important thing to understand about the first role-playing games is that the people who created them were already role-playing when playing other games. So their role-playing games weren’t designed as rules for role-playing. They didn’t need rules for role-playing in other games, so why would they need them in a role-playing game? Rather, the rules were designed to not get in the way of role-playing.
This is why the combat system† in original D&D is anemic compared to the wargames with Gygax’s or Arneson’s name on them. This is why the combat in the main three classic Traveller books is anemic compared to the wargames Marc Miller had previously designed.
†While original D&D said to use Chainmail, neither of the creators did so in practice. Arneson said he abandoned Chainmail early on in favor of developing the “alternate” combat system. Gygax said he never used Chainmail for D&D combat.