Of course you are assuming the warforged arrived in Faerun on day one of the campaign? Why?
They likely arrived recently, because Warforged didn't exist in the setting until someone asked to play one and convinced the DM.
Also, I've never seen the "fell through a portal trope" extended into "I fell through a portal years ago and integrated into society" unless they fell through as a child. Warforged are built, therefore there are no warforged children. Sure, they could say that the character has since become a stable pillar of the community in whatever town, but odds are the DM is going to have them appearing within the past month instead.
Because they are neither omniscient nor omnipotent.
Neither is the US Military, but we map the borders of our country within a matter of feet or inches. Unless the landscape actually changes drastically, being immortal and using a spell such as Arcane Eye or Fly or simply looking through the eyes of another person, you should be just as capable of accurate mapping as we were in the 1940's with the invention of the Airplane.
You also have illusion magic, mind warping magic, creatures that can devastate and drastically change continents and worlds in a matter of days, planes whose nature is malleable, and so on...
The largest illusion spell is Mirage Arcane, which covers only a square mile, incredibly tiny in terms of geograpy of a world
Mind Warping magic can effect a single creature generally, and normally cannot be cast upon a thing like a scrying sensor. Also, one has to wonder why you would risk mind control a powerful entity for the purpose of ignoring your forest, when instead you could simply hide in the forest and not deal with those pesky saves.
A creature like that attacking an area would be like an earthquake or a meteor impact, people tend to notice things like that and then you can survey again. Also, there is very little evidence that something uncontrollable like that tends to hit the big names, like The Nine Hells or Mount Celestia on a regular basis.
So yeah, the planes might be malleable, but how malleable becomes the question. Generally, I thought that a plane of existence ruled over by a powerful entity was shaped by that entity, meaning that they would be generally stable as long as the controlling entity was stable. But unless they drastically change from year to year, it would seem like you could at least get a good sense of the place over time.
For certain places yes... for the entirety of creation, I'm not buying it.
Why not? Many settings before Planescape and Spelljammer did exactly that, gave us maps of the entirety of creation. Eberron said "here are the planes, here is how they formed, this is how the interact" Dragonlance made it even easier by limiting the number of planes in existence. Forgotten Realms keeps going "oh, that was here on our planet too" but has stayed fairly consistent about the shape of reality when it came to the planes of existence.
Then Planescape and Spelljammer went... "nah, you guys are wrong, this is what it all
really looks like", and we started this whole mess of "well, this person thinks this is true, but it is a tuesday so that shifted over there and really if you look at it while standing upside down that person seems to be right"
And, while you can choose to not recognize any normal setting and be fine, because it isn't the setting you play in, choosing not to recognize those two meta-settings, suddenly makes you wrong about the shape of reality that you are playing with. I've seen plenty of people post "this isn't true in my homebrew, the cosmology looks like this" and people respond with "that's cool man, that is the truth within your crystal sphere, but outside of that you're wrong and it looks like this because Spelljammer says so" Even in this thread we had Demeritous I believe going on about how it is too late to complain about these things because it was done 20 years ago and that is the truth of DnD now.
Whether Sigil exists and whether it is known by any particular person or group of people (or for that matter believed to truly exist) are entirely different questions. Though I'm a little confused about different places that take over it's role... what exactly is Sigil's role and what other places take over it in other settings?
Off the top of my head, I believe in the Magic universe (which now matters) Dominaria or something is the "meeting point of reality" I've often heard of Dis or The City of Brass being giant inter-planar market places and meeting places, which is a major role of Sigil as I've heard it. I'm not fully familiar with a lot of settings, but I think Hollow World had a center of reality where all things met.
So now you're determining what is or isn't canon for Dragonlance... I'm failing to see why Planescape is giving you such issues. Can you actually cite where Planescape is mentioned in DL or where DL is mentioned/subverted/changed by the Planescape campaign setting? Your complaints just feel like alot of hand wringing from someone who hasn't really read the Planescape setting, and who tends to get it confused with the Great Wheel cosmology (which existed way before Planescape did and was already being used to tie TSR's settings together... though as shown above you seem to have no problem selectively ignoring the earlier connections).
So, Planescape does not use the Great Wheel Cosmology as it's map? I thought the point of Sigil was that it was the center of the wheel?
Sure it is... Belief shapes the multiverse is one of the fundamental themes of the Planescape setting... and one of the biggest differences between Planescape as a setting vs. The Great Wheel as a cosmology.
But they use the same basic map right? So... the biggest difference between them is that the Great Wheel says "this is what things look like" and Planescape says "This is what things look like because the majority of people believe it should look that way"
Which fundamentally mean the exact same thing. Reality is shaped by belief, people believe thing so it is true, people look for other truths, they will find the reality shaped by the majority belief. Unless every individual is capable of reshaping reality completely, in which case... how anything could possible get accomplished or done is a mystery to me.
Lol.... No one is shoving their preferences down your throat. IMO other settings... FR, DL, GH, etc. don't share the themes or tropes of Planescape and they've never been forced on them. Now if you don't like the GW cosmology cool but it's been here since 1e and well they've made it pretty clear it's not going anywhere because people either like it and/or it can be easily ignored.
It can be ignored, but it is an aggravation in a lot of ways.
And honestly, now that this discussion has gone further, I'm starting to wonder what does Planescape offer?
It isn't the Wheel, they are somehow completely different even though they use the same map. It allows you to visit all the planes of existence, like The Nine Hells and Mount Celestia... which you could do anyways in each individual setting. None of it is actually true, just what people think might be true... Is literally the only piece of Planescape the creation of Sigil? Is it all simply reduced down to the setting for going to a big city where you can walk to anyplace in reality if you felt like it?
At that point... can't we just reduce it down to "here is the guide for Sigil" and be done with it? We don't need to say anything about the plane of existence or whether or not Eberron and Krynn are connected, if all you have is Sigil, that seems to be enough.
