Let the players play! MWFs in old time modules

I have a longstanding beef with modules that have some rule written into them that forbids the players from learning important information or performing certain actions that they might otherwise reasonably have a chance of learning/doing. I call that a Module Writers Fiat (MWF). Did Sir Gary Gygaxalot ever include one in his modules? Not that I'm aware of, but here are some old timey modges that did incorporate MWFs:

A1--Slave Pits of the Undercity 

There is an MWF proclaiming that the PCs are not allowed to figure out how to operate the firewagon in the courtyard of the slaver temple. Killjoy.

A3--Assault on the Aerie of the Slave Lords

The informants in Suderheim that dole out cryptic clues for finding the entrance to the slaver lair will not provide any further assistance beyond repeating their single line of dialog, even though it would certainly help the cause if they would just say "Go to the White Knight Tavern on the Bowery at 4th Street and ask for Phebe."

L1--Secret of Bone Hill

Tales from the rumor table are
only known by NPCs of Level, so the regular townsfolk will have no information to provide even though many of the rumors on the list are pretty prosaic and seem like exactly the kind of gossip you might catch from chatting with the locals at the tavern. 

N1--Against the Cult of the Reptile God

The elves hired by the mayor are not allowed to help the PCs, instead insisting on working alone to stop the Cult. There's no way that two low-level elves are going to do jack squat against the cult on their own. It's not like two freakin' elves are going to tip the balance of power too far in the party's favor if that's the MW's concern--which it obviously wasn't since there is a 7th level MU in town who the PCs are expected to befriend if they want any chance of succeeding at this modge. 

X3--Curse of Xanathon  

This turkey has at least two MWFs. 1) Similar to A3 above, once they've dropped their cryptic clues, neither the dwarf nor the High Priest/Beggar will elaborate on their knowledge regarding the goings on at the Ducal Barracks, even though getting the PCs to investigate the barracks is absolutely essential to the continued play of the module. 2) PCs are not allowed to find the secret door to Xanathon's lab until after they return from the mountains with his soul in a jar. I wouldn't be terribly surprised if there were three or four more MWFs to be found in this one.

U1--Super Sinister Secret of Saltmarsh

PCs are not allowed to find out why the Persons of Lizardliness are on the smugglers ship at the end of the module, and for good reason: that knowledge would decrease sales of the sequel module!

Interestingly, the sequel in question--U2 Diabolical Danger at Dunwater--does not have an MWF preventing PCs from entering the Lizard Lair through the front door even though this could immediately upend the adventure. Presumably this is because you've already bought the modge; whether you actually play it or not is irrelevant. 

What U2 has instead is a practical design feature making the front entrance unlikely to be used: you have to swim to use it. No second level party is going to want to swim their way into a cave full of lizardmen. Or women. Practical Design Features (PDFs?) are always a better choice than MWFs.