Originally Posted by
Knaight
I'd argue some of this (starting with how a group of players all familiar with each other is arguably the default and not a special condition), but a broader point is that this varies highly between the cultures attached to different games. With D&D, or GURPS, or HERO, or Rolemaster, or really most high crunch systems this is the assumption. In lighter systems it routinely isn't. I mostly GM and play Fudge*, and it explicitly doesn't use the standard-variant setup, instead having multiple places where there are essentially a bunch of variants posited with something to the effect of "pick one or write your own"** written somewhere. Nobody with a clue is going into a Fudge game expecting standardized rules.
*Where the GM:Play ratio is something like 35:1.
**It's probably a paragraph or three, as Stephan O'Sullivan isn't great at being concise, but that's the result.