So your presumption of how the module should play, is how it is supposed to play...so essentially you are saying I and everyone differing from your opinion is playing the game wrong.
ok.
1- You have offered no evidence, you made no arguments, only words on a screen, like tears in the rain.
1a- Defend your XGE Awarding Magic Item thesis that the intent is to limit party power.
You are supposing an inference. The 5e DMG rules are wafer thin in terms of awarding Magic Items guidance, the weakest in the history of the game. Page 133 of the DMG is minuscule when compared to the Treasure Tables of 1e MM plus the 1e DMG. This is true when 2e, 3e, and 4e rules are looked at vis a vis 5e treasure rules.
The niche of needing more substantive Magic Item Awarding guidelines was present, and the D&D team recognized this, and evolved to fill the niche. Please defend your stated presumption of design intent.
2- The ‘point’ of any survival scenario is to mitigate the exposure to deleterious environmental factors to a manageable level. If rooms 1-38 were filled or filling up with 55 damage lava, then yes the only way to play would be to book it or else cook it.
3 points of poison damage an hour is not lava.
I have played this adventure at least 3 times in my life. Each time I’ve seen fissures in the group develop over fleeing fast and far away as immediately as possible, or doing some exploration.
The rooms in the poison cloud are fun and evocative precisely so that ones desire for self preservation conflicts with the desire to see what other interesting things are to be found.
This is Quintessential 1e design in my opinion; players expect to be intelligent enough to solve the challenges, without being wise enough to avoid the whole mishegas to begin with. (Which is how Gary G characterized his relationship to smoking).
To use an analogy if one asked people to give a mathematical operation that results in the whole number ‘2’, one might presume the likely answer given would be 1+1. Clearly this is not the sole answer though. If 1+1 is supposed to be the correct answer, than one needs to reform the question!
If exploring cool rooms with encounters through poison clouds while staying alive, if exploration of the temple is not the true goal, then why make it cool?
Group Int(Investigation) or Wis(Survival) checks to determine how long it takes to find a safe route out and then applying damage based off the time rolled could adjudicate this in a matter of moments. Of course then the module would not be a classic.
To bring this sub conversation back to the point of this thread, in ‘Adventure Path’, Prakriti outlined, I think it is entirely reasonable to warn DMs whose only experience has been 5e that loot in Tam & White Plume is handled a bit differently than in most 5e products.
Also, Paul, thank you for being a good sport.