The problem is that Marvel CAN'T enter those territories. Marvel is now bought and paid for Disney and publicly synonymous with it so there's no way that Marvel can go beyond PG-13. So nothing like Joker 2019 or so on is gonna happen in the MCU. Disney will always resist attempts to go adult, it's part of their long-term brand philosophy that's not gonna change and is central to everything they do from toys to theme parks (which after all make more money than the movies do).
Nothing like the Netflix Marvel shows are gonna happen either.