A game dev and a dm can set up a fight with goblins or let you sneak around, what's the difference, what can a game dev not do that a dm can, they both setup encounters and you play them
A DM can improvise on the fly.
Game devs have a budget and have to put more effort into creating levels than a DM has to.
You want a player in a PC game to be able to enter every house in a city with 200 houses? That's 200 interiors for the level designers to build.
You want there to be NPCs in those houses that have quests for you?
Great, let's say 20% of these houses have a side quest in them, that's already a shitload of quests for the writers to come up with.
A DM can just quickly improvise and say "Yeah ok you can go in this house."
Describes the interior of the house in two sentences.
Describes the NPCs sitting inside.
Boom, it's that easy. Content created on the fly in the DM's head with zero budget.
You can't do that in a PC game.