How did they pick their first quest? What rumours? Rumours of adventure locations that the DM hasn't created yet? How did they travel to the location that doesn't exist yet? How did they know where it was? How did the DM know how long it would take to get there? So many questions.
And note, without the DM having anything outside the town prepped, what could the players actually do? It's not like they can say, "Hey, I want to check out X" when nothing outside the town has been detailed yet.
I'd LOVE to see you be able to "just in time" create using D&D. That would be very impressive.
I can't tell if you're being serious here or not. Because shockingly, you don't need to
prep an area to have rumors about it. GMs
have imagination, you know. We can come up with ideas without having to come up with stats, and we can come up with stats on the fly.
And we can create rumors
and then prep the area based on what, if any, rumors the PCs decided to follow up on.
And of
course the players can check out things that haven't been detailed, because
they can come up with ideas on the fly as well. Presumably the PCs have their own goals and interests, even if nothing else in the world has been fleshed out.
In last Friday's game, the bard's player wanted to know if anyone was putting on a performance. The GM said "sure" and to the best of my knowledge, came up with the performance on the fly--they certainly weren't part of the scene until the player asked about it. (Either that or they had a "random performers" encounter prepped out and ready to use at a moment's notice, which is another thing you keep forgetting the GM can do). In either case, the performers weren't a
planned encounter. The player wanted to do something that was important to his character and the GM was able to instantly respond.
Wow, that sounds like the most boring adventure I've seen. A couple of stat blocks for six encounters? Maybe a pet? No NPC's, no prisoners, nothing? Sure, if we're going to make the most basic, prosaic, boring adventures possible, then sure. No worries.
You're the one who came up with the Simple Dungeon Of Six Encounters, not me.
And to be frank, I am not going to put in a lot of effort to come up with an example for you. I have an
actual game to prep for.
It's funny. The first scenario in Lost Mines of Phandelver has 8 encounters. The Cragmaw hideout. Now, this is for 1st level characters (note, I notice you immediately chose the simplest, LOWEST level adventure you could to illustrate how easy it was. Let's see you try that with a 9th level party, but, I digress).
Sure. Instead of low-level goblins, it's giants, or a outpost of a powerful bandit group.
It's a group of uncaring spellcasters using the area to create powerful, reality-warping spells that's been having a spill-over effect into the surrounding countryside. Can the PCs stop the spellcasters? Can they find a way to restore the countryside?
It's where the princess and her retinue of guards has run away to so she can gather forces to fight against her father, the king, who has become warmongering in his old age, while the king thinks she's been kidnapped and hires the PCs to get her back. Will the PCs realize the truth in time? Will they join with the princess or with the king?
It's where dwarfs or kobolds or some other mining folk have accidentally uncovered an ancient portal to another plane, and now weird/eldritch/evil beings are coming through. Can the PCs find a way to close the portal... or will they go through it?
It's where two armies are gathering to clash, uncaring that their battle may destroy a village in the middle of town. Can the PCs protect the village or try to convince the generals to end their battle?
All for the simplest 1st level adventure. Still, twice as many stat blocks as you were using. And a heck of a lot more interesting adventure than a handful of goblins guarding a pie.
What pie?
You have a
bad habit of strawmanning. First you take the idea that some people like to have some depth to the world and spin this into "people can't play without a 300-page setting guide," and now you took what was a simple exercise in creating six encounters into "this is boring and it's about goblins guarding a pie."