hawkeyefan
Legend
This is an odd example, because there are no GM-to-player or player-to-player social mechanics in those systems.
I haven't dug up my copy of the 3E PHB, but this is from the online 3.5 SRD:
You can change the attitudes of others (nonplayer characters) with a successful Diplomacy check
Not that 3.x D&D is the best example of it, but I think the ability for a PC to influence a NPC where the outcome is determined by a roll is a pretty big part of what we’re talking about, as well.
I don't really think that “act it out to the best of your ability and I as GM will decide” is all that great an approach.
I like when the GM is involved in the factors at play...the NPCs starting attitude, for example....and then the resolution is left up to the roll. The roll is what determines how well the PC performed, how diplomatic or persuasive or deceptive they were, and therefore the outcome.
This puts all the GM’s judgment into establishing the situation and the chances before hand, and then leaves the outcome to the roll. I prefer that to a GM interpreting a roll or in the absence of a roll, interpreting the quality of the player’s attempt, and then deciding the outcome.
The GM deciding the outcome is probably the most relevant bit. Many will be fine with that. Others won’t.