>>713383254
Cause early RPGs thought of dungeons as actual dungeons and not video game levels.
You go into it, explore as much as you can with the resources you have and back out, then repeat until you're proficient enough at navigating it that you can make it to the end with little issues.
It's how a real group of adventurers would go about it rather than just treating it like a singular video game level.
Even some modern RPGs like Persona and Etrian Odyssey keep this type of dungeon design going.