Again, bad faith and the social contract. I mean, if you want to play with a jerk like that you can, but the game doesn't say that the DM should be a douche.
I did not say that it says they
should be one, so that's a bit specious. Instead, I'm saying what it
does say to do has a great risk of
inviting "douche" behavior, and that it both intentionally excluded possible opt-in means to avoid that, and intentionally
Should does not imply obligation, at least not on the DM's part. Should implies that the players are playing the game and paying attention to details, and have a modicum of common sense. They should be able to figure out if something is possible or not, or at least have a very good idea. The players have an obligation to pay attention and try to think things through.
The only way the player can acquire information is if the DM provides it, in 5e. There is no source of information
other than the DM. Thus, if the player "should" have such knowledge, it is necessary that the DM
should provide that knowledge.
Is there any other way for the player to have that knowledge? You mention the player being obligated to pay attention, but how can they pay attention to signals that aren't being sent? It doesn't require a horrible DM to fail to send these signals. A great many
mediocre DMs fall into this problem, it may in fact be one of the things
keeping them mediocre as opposed to good.
Hence the special reagents. It's not something they can do normally.
I don't see how these are any different. They'll have heard about the Fire Swamps and can ask around to find out more. I mean, I suppose if they just don't bother to talk to anyone or see if anyone in the group knows about the Fire Swamps and charges in, they may not know it's impossible, but that's on them.
I don't assume incompetence or malice on the part of the players or DM. I assume the opposite, since the vast majority of DMs and players are at the very least competent. That means that I am assuming that the players tried to find out information(competence) and that the DM didn't try to jerk them around(malice).
With no incompetence or malice involved, the players should have a good idea of what is possible and what is not.
Which just sounds like "the DM can do no wrong, as long as you presume they can do no wrong." It's circular.
These things coming up suddenly, without explanation, or being planned for specifically so that they can be used to shut down possible player choices,
is exactly what gives evidence that the DM is doing something wrong.
It's very easy to figure this out in short order. Players are good at realizing when the DM is shooting all of their ideas down and just coming up with weak justifications.
Yes. That's literally what I've been saying.
This is even easier to figure out. Players have a good idea of what is reasonable and what isn't. If the player rolls a 23 and the DM says, "Not high enough," the player is going to know that the DM is jerking him around.
I'm not so sure about that! This sort of thing gets a pass all the time, where a skeptical DM "allows" something and then sets an (explicit) sky-high DC, or forces a player to roll seven times in a row, or whatever else. It's hard to distinguish "DM is jerking [me] around" from "DM is giving unlikely/implausible actions a chance of success."
Illusionism is the hardest thing to figure out. The rest is fairly easy. Illusionism isn't Mother May I, though. Mother May I is when the players are forced to get explicit permission from the DM to do things.
I wasn't talking about illusionism though. Illusionism is where the players aren't allowed to know that it doesn't matter if they take a boat or teleport or ride horses, they'll be ambushed by the Skull Clan along the way, or "quantum ogres," or otherwise superficially granting players choices while never actually deviating from the planned path.
Overt "thwarter-in-chief" stuff occurs when players must get explicit permission from the DM to do things.
Covert "thwarter-in-chief" occurs when the DM makes sure (either by inventing things on the spot, or by exploiting prep, or by planning super far in advance) that there's only one valid option, and explains in turn why each attempt the players make fails to work: it's not that it makes no difference which path the players take, it's that there is only one valid path, and the DM ensures that that path gets taken, by hook or by crook.
I can.
DMG page 4
"That said, your goal isn't to slaughter the adventurers but to create a campaign world that revolves around their actions and
decisions, and to keep your players coming back for more."
That says don't be a jerk(thwarter in chief).
It doesn't, actually. It says not to kill the characters. "A campaign world that revolves around their actions and decisions" can be one where there was only ever one decision they were allowed to take. "Keep your players coming back for more" is closer, but as I said, this stuff can be subtle.
DMG page 26
"Listen to the players' ideas, and say yes if you can."
No thwarter allowed there.
And yet that would exactly contradict what
numerous posters have said here. I have proposed this exact thing. Guess what? Almost everyone opposed to the use of the "MMI" label has called this "say yes if you can" stance
bad. If that line is supposed to be so important, why do so many people disagree with me when I say it in my own words?
DMG page 287
"As always, it's better to say yes and use the player's desire as an opportunity to develop the character's story and that of your world, rather than shutting down possibilities."
This also says no thwarter in chief
Cool! That's actually a legit citation that counteracts this.
Why, then, do people still defend the Rustic Hospitality scene, or some of the other examples I've given, as totally acceptable? The game
actually does say that this is bad. Why do people then say it is good, and in keeping with the text, when it is not?
PHB page 4
"Playing D&D is an exercise in collaborative creation. You and your friends create epic stories filled with tension and memorable drama. You create silly in-jokes that make you laugh years later. The dice will be cruel to you, but you will soldier on. Your collective creativity will build stories that you will tell again and again, ranging from the utterly absurd to the stuff of legend."
That strongly implies that thwarter in chief is wrong.
It...really doesn't. It doesn't really say
anything about that--particularly because, as several people have said, 5e puts all storytelling power in the DM's hands. The PHB might give a nice spin on it, but ultimately, it is the DM, and
only the DM, who tells the stories. The players are simply there to be entertained.
PHB page 4
"D&D is a game that teaches you to look for the clever solution, share the sudden idea that can overcome a problem, and push yourself to imagine what could be, rather than simply accept what is."
That says no thwarter in chief, since clever solutions to overcome a problem would be irrelevant if thwarting was okay.
Ah, does it though? It is a well-known problem for a variety of game-makers that a solution which seems clever and effective and obvious
to the maker can be incredibly obtuse and weird and inappropriate
to the user. Sierra adventure games, for example, were
notorious for this problem. Authors, likewise, often struggle with telling mystery stories, because the author's intense and unique familiarity with the story makes it significantly harder to determine whether a particular clue or set of clues is obvious or not.
So, no, this really doesn't do much of anything. It's a pretty puff-piece, a nice bit of fluff, but it doesn't actually constrain anything.
Out of the five examples, two hits. One of them has been
explicitly rejected by several people in this thread, IIRC
@Crimson Longinus being one of them (please correct me if I'm wrong on that!) The other
explicitly contradicts the Rustic Hospitality example, among others, which numerous people in this thread have defended as undeniably in keeping with the instructions and rules of 5e, even as they grant that it was not wisely-handled.
Is there any wonder why people find such problems? The things you cite have been rejected by people in this thread--not to mention the broader practice of 5e DMing--as
not true of 5e, despite being actually written in the books.