iserith
Magic Wordsmith
If you were running a published adventure, would you be fine with players reading that adventure and learning plot twists, NPC motivations, and the like?
Yes. Players frequently replay my one-shots with full knowledge of what to expect, sometimes many times over. This just isn't a problem in my experience.
That said, there is no module I have ever run as-is because they are in my opinion frequently terrible. Especially the plot-based ones.
I personally would not, and have had this come up before when I was a player years ago (AD&D 2nd era). I was very angry at another player who read the module and his character knew where all the loot was hidden and what was cursed, the vulnerabilities of all the monsters, how to disarm every trap and solve every puzzle. Called him a cheater to be exact.
This is more extreme then reading the MM, but not an absurb reduction - it's players with knowledge and using it. The DM could change thing around (and did after the end of that all-day session), but only after it became obvious what was happening - i.e. "the damage was done".
My question is less about what people's particular opinions are on this (which are varied and inconsistent in my view) but where the opinion originated, as it pertains to separation of player and character knowledge. Was it organic or did it arise from some rules years ago?