Funny, I thought a roleplaying game was a game which involved roleplaying. Disco Elysium doesn't even have a battle system and it's the best RPG I've played in years.

That's a definition of RPG that hasn't really fit strictly in years. Even if it did, the aspect of RPGs that OP is discussing isn't actually that part, and isn't super inherent to open-world games or RPGs anyway. Hades serves as interesting contrast to the dynamic OP is talking about