Please explain to me how I've misrepresented you. That's how I read your statement.
Well, let's see.
I explained a thing which is lost by having the GM sew up every single detail of the world before the players ever arrive, an aspect of player agency.
I specified that there really is a value--flexibility, discoverability, authenticity to the IRL cultural experience of pre-modern civilizations--to having a world where, within a certain boundary things are well-defined, probably quite a large boundary, but beyond that boundary, it becomes "HIC SVNT DRACONES",
terra incognita. Not only does this add more similarity to what was in fact true (of medieval
culture, naturally) in our real world, it ensures that the GM has an important tool for addressing problems that might come up: the freedom to build (not just randomly conjure up, but actually invest effort to
create) new elements of the world.
This is something genuinely valuable, even by the lens of verisimilitude, in addition to benefits on perpendicular axes of useful GMing tools and other things.
None of this has anything to do with forcing GMs to do anything. Instead, it is about keeping options open. To write this off as being, ah,it's literally just petulantly demanding the GM give you all your toys...is extremely frustrating, and a gross misrepresentation.
I legitimately tried to present to you something I thought you would find valuable.