There's a significant amount of guidance throughout the DMG, I will say that the 2024 DMG does a better job of it than the 2014 one did. But how much is enough? You can talk all you want about how the goal of the game is to ensure everyone is having fun, listening to your players, finding your own style. But none of that will ever really change the person running the game. They're already going to inherently understand that basic advice and just need a bit of help making it happen or they don't.
DMing a RPG is hard. Being a player in an RPG is hard.
Unless you play an RPG like a board game/war game where you'd say "my character moves three squares forward and takes the attack action!", an RPG has these parts:
*RPGs are complex. Even the rules lite ones have a lot of rules. And a lot of the rules are vague.
*The basic idea of "role playing" is extremely hard for many people. Just the "Okay, imagine your in a castle and a dragon flies overhead", is already hard for a lot of people to grasp. And going the step further to say "and imagine your Darg the Dwarf Warlock in that castle" is even harder.
*Basic imagination is hard, people struggle with just "imagine a dragon by a tree".
*Any small group social activity is hard. To say a great many people don't know how to socialize and be social is an understatement.
*Playing in a group is hard. Teamwork is hard. Far too many players are the abrasive Lone Wolf type...
The DM gets all the above, plus:
*The DM is in charge by an odd default. As the DM is running the game, they can ask players to leave. This gives the DM the 'in charge' part where they can tell players what to do during the game. If a player is disruptive or worse, the DM can ask them to leave. Players can't do that...and most won't anyway.
*As the DM controls game reality, they control the pacing. If the game slows down to near nothing happening, it's all because the DM is not taking any action.
*DMs have to create and make up everything for the game, as the vast majority of players just sit back and ask to be entertained.
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Lots of hard stuff.....not everyone can just pick up a D20 and be Amazing.
Some people to grow and change with experience.....but a lot do not. For example, a player might have played RPGs for years, but all their characters have forever had the personality of that player, as they refuse to role play and only play characters as 'themselves'. Some Improv DMs will claim to remember everything they randomly make, and get upset if you point out their often mistakes.