No one said I had to succeed. What I said was, "I use diplomacy on the chamberlain to see the king" to which the DM replied, "The chamberlain sticks his fingers in his ears and cries 'La la la I can't hear you".
If the DM did, in fact do that, I most certainly would leave the game.
But, rolling this back to the original point of this thread, casters vs non-casters, it's extremely telling that the diplomacy skill (the only way a non-caster can mechanically affect the reactions of an NPC) get's hosed, while, a simple 1st level wizard spell (Charm Person) would get me exactly what I want without any fuss.
This is why I talk about the disparity in power. The non-casters are at the whim of DM's who feel entitled to change the rules whenever they feel like it, while the casters can generally know that the spells they cast will be ruled upon in a fair manner. Heck, you, N'raac, have talked at length about how clear interpretations of the spell effects makes for a better game. I cast a Silent Still Charm Person on the Chamberlain and he fails his save. Do I get to see the king or not?
Or, do you simply Auto-save the Chamberlain to protect your scenario. After all, you've auto-failed the fighter for trying diplomacy, so, it should be the same thing no?
And this whole game of trying to find equivalency in DM power is laughable. We've already stated that the DM has total control over the game world, barring a few, generally fairly minor, exceptions. Of course he does. That's not what GM Force refers to. GM Force refers to DM's actively changing the rules in the middle of the game for the purpose of delineating specific actions to the players.
IOW, starting your campaign in Waterdeep is not an example of GM Force. Telling a player he can't play a Cyborg Ninja is not an example of GM Force. An example of GM Force is any time, during play the GM over rules the resolution mechanics of the game.