To donavanm's point that you need writers to create engaging content, as you've pointed out Dwarf Fortress has writers--they're just operating on a different level.
But I still think the learning curve is a big part of it. Just look at how many "Get started with Dwarf Fortress" tutorials are out there.
I'm also not sure its fair to consider DF's writing as similar to donavanm's -- they're not operating at a different level so much as a totally different task. donavanm's writer as I understand it is trying to lead the player through a story, whereas DF's trying to produce a story through the player. The former produces an overarching theme, plot, characters, etc. The latter produces pieces that could fit in a story (or stories), and hope it will occur as an emergent phenomena of play.
It's like writing a protocol versus using one; you could say both are doing software engineering, but they're very, very different kinds of software engineering, and require totally different thinking.
Notably, story-component-writing probably also scales pretty well (the engine develops it out), while story-writing does not. Which of course is true of procedural games in general. You get the engine and the pieces right, and you've got exponentially many scenarios to explore (the problem is that, if you do it wrong, you have exponentially many scenarios that you don't want/care to explore ~~ No Man's Sky)
The genius of Minecraft is that it's a vast canvas for you to shape, not an interesting world to study. The purely procedurally generated world that it generates are fun to build on they just aren't that interesting after you've experienced it for a bit.
I don't think they were only talking about an overarching large scale story, but also the small scale side stories that happen throughout the world. Allowing the player to overhearing the backstory of 2 train robbers right before they start the robbery, or coming up with a back story for an abandoned house and telling it through the items left around. Small additions that add flavor and detail to the world. When you add to that some game mechanics around choosing to aid or stop the train robbers, choosing to find the lost treasure hinted at by a journal found in the abandoned house etc..., and then the game world reacts and changes based on those actions, to me, you're doing exactly what Dwarf Fortress is doing. To me the difference is scale (granted it's a huge difference and I think much more difficult to pull of right). Dwarf Fortress does it on a much grander level that allows for more variation and more genuinely unexpected emergent behavior.
The creators of Dwarf Fortress write small stories that add flavor to the world and then they add systems to make those stories possible. It requires much more human effort to develop than just piecing together systems and hoping that the interactions are interesting, which is what I think donavanm meant by being less scaleable.
