I just have to say this seems like a really odd take for you EzekielRaiden. Your takes are normally so grounded in logic. Can we start with paragraph 2:
I appreciate the compliment, even if I have failed to live up to that standard this time.
I assume any experienced DM would give reasons why a place exists. They would also foreshadow it. And many would have a historical component to its uniqueness.
But that isn't what was described above. What was described, upthread, was someone pointing to a passage in their 20 (or was it 25?) year old compendium of setting notes. This isn't the first time such things have come up either. Multiple actual people--specific posters on this forum--reserve the right to simply
declare that sort of thing if they feel it makes sense. Or, worse, to
not declare it, but have it exist nonetheless.
I would not invent this sort of thing if people had not expressly said it's what they do, have done, or reserve the right to do.
Paragraph 1:
Does that pyromancer complain when they have a combat encounter where the creature has fire immunity? It is part of the game sometimes (not always). A tit-for-tat. A, "Hey, I let you blast things with your fireball three games in a row. It was fun, huh? Now you encounter someone with counterspell."
A single encounter is quite a bit different from an entire adventure designed such that it screws over a specific party member. And if you want an actual, IRL example of this kind of stuff, not one I invented off the top of my head: People complaining about undead-centric adventures or campaigns when playing as Rogue, because Rogue (at least in 3e) could not do sneak attack damage to undead for ill-explained simulationist reasons. (Something to the effect of "undead don't have functional anatomy, so they have no special weak points," as though it couldn't still be the case that they have weaker spots to attack
for different reasons...)
Again, I never liked that style being the only style. But sometimes, players need to overcome obstacles. And a place where their strengths are not strengths, that should be looked at as a challenge, not something to complain about.
But such things should either (a) not be blanket "now you just suck for this whole adventure, because the thing you specialized into is worthless for now," OR (b) should be EXTREMELY well-telegraphed so the player has a chance to prepare, or potentially even to look for a solution of some kind. E.g., with the Rogues and undead thing above, maybe they do some digging and find out that
holy weapons can still harm undead that way--but the character has a rocky relationship with faith. Suddenly, what was just a crappy blanket "nope, you don't get to be a fun rogue, you get to be a Wal Mart brand Fighter" now becomes a cool opportunity. What is the rogue willing to do to keep their edge (in this case, almost literally
edge)? Will they try to mend their ways and find a good-guy deity to petition? Or perhaps they turn to something a bit...darker? After all, "holy" in D&D just means an enchantment from a divine source, not from a
good source. Etc.
You seem to be taking it as a given that the GM will only do things in the most maximal extent of good faith. Folks here on ENWorld, to say nothing of the wider internet, have more than once told me otherwise, when it comes to doing the work of justifying why a thing should be the case.