I recently argued that pen & paper roleplaying had fallen out of favor because it is so much harder to organize a tabletop session than to organize some other game online. But the 5th edition starter set has resulted in a lot of podcasts and YouTube videos of different groups recording their session of playing the same adventure with the same rules. And one can't help but notice that the quality varies widely. So if you think of a hypothetical group of teenagers trying to get into D&D without outside help, just armed with the Starter Set and the Basic Rules pdf, there is an obvious pitfall: A DM who is new to both playing and leading a game is quite likely to be bad at it. And that might turn the whole group away from that hobby.

Now the good news is that D&D, even if some people would like you to think otherwise, is not *one* game but a million different ones. There is no such thing as the one true way to play Dungeons & Dragons, however much some people might preach their way. You can run a game with an adventure that has a predefined story with a beginning, middle, and end. You can also run a game which is more or less pure sandbox, with no story at all. And everything in between.

Those two extremes point towards two main qualities that a DM must have: To run an adventure with a fixed story and fixed encounters, he must know the adventure very well, know the rules, and come to the session well prepared. Especially if you play tactical encounters with figurines/tokens on a map, preparation makes a huge difference on how smooth and fast that is going to run. The second quality comes from the sandbox aspect of D&D: A DM must be good at improvising. Even if the players are supposed to follow a story, it is always possible that they make some unexpected decision that leads the events in a different direction. And the DM must be able to come up with a believable response of the game world to whatever action the players perform. You probably hadn't thought the wizard would use a fireball in the bar room brawl, so how does your city react to the tavern being on fire?

Every DM needs both of those qualities. Being good at improvisation doesn't absolve you from having to know the rules and your game world. Whatever you improvise today will be canon lore tomorrow, so you will have to remember what told your players about some NPC or location. And if you make an improvised rules decision, that better fit with the existing rules. Otherwise your overly generous bonus you gave a player for throwing sand in his enemies' eyes will become a new house rule that leads to every player carrying a bag of sand around.

In my eyes a computer usually makes not a great DM. A computer is good at consistency and speedy delivery of prepared rules and story. But a computer is lousy at improvisation. I'm currently playing Divinity: Original Sin, which makes a great effort to have the game world react in different ways to different approaches that you can take in any given situation. But you can't help but notice that things like destructible environment are frequently limited: You throw a fireball into a room and the chair gets destroyed, but the tapestry doesn't; the chair was programmed as possibly destructible object, the tapestry is just a texture on the wall and can't really be interacted with. Thus typical computer game problems of world-saving fantasy heroes being stopped by a knee-high fence.

But if you compare a computer game with a tabletop game, it is perfectly possible for the DM of a tabletop game to be worse than the computer. A human DM can be bad at *both* improvising and prepared content. In 30 years of tabletop roleplaying I certainly met my fair share of bad DMs that would have made me choose a computer instead if I had been given the option. A computer is some sort of baseline mediocre at running a good game, and many human DMs can do a lot better, which is why I prefer pen & paper roleplaying to the computer version. But I can just as well imagine a group of teenagers trying out D&D for the first time with a DM who is badly prepared and bad at improvising, and concluding that their computer games are better than that.