It's a spell. Works differently.
Right. I guess that's why, say, D&D monsters who're immune to fear are also immune to Fear spells, while PCs aren't. And hey, it must be why the designers decided to call it a Fear spell and not, say, Run Away For No Reason.
Fear, like anger and a lot of other human emotions, is a response to something. However the spell that induces such an emotion supposedly operates, and whatever system you're playing with, is besides the point.
PCs and uber tough monsters cannot be intimidated by mere dice rolls. Use your fukkin' common sense.
Picture our PC at the head of an army of 10,000 pissed off Balrogs, telling Sauron to get on his knees. You're really of the opinion that Sauron couldn't possibly be intimidated in that situation?
Now picture the roles of the PC & Sauron were reversed. Again you're really of the opinion that the PC couldn't possibly be intimidated?
No matter how tough a PC is, a pit fiend should never be intimidated by a mere mortal. Nor should a PLAYER CHARACTER be intimidated persuaded by mere dice rolls.
I don't disagree that it should be difficult for a mortal human being to come up with a way to intimidate an immortal daemon. But as long as the daemon in question isn't the super duper supreme divinity of all time and existence, it probably shouldn't be outright impossible. If it's possible for our daemon to get royally fucked in some manner, the mortal can ensure it happens, and our daemon is bright enough to understand the causal relationship, then there's an in-fiction reason the daemon shouldn't be immune to intimidation.
As for PCs... Why not? I ask because you've offered no reason PCs should be partially exempt from social conflicts, and the only reason I can think of is that it potentially forces PCs to act in character in situations where their players would rather act out of character. Which, at least to me, isn't a bad thing at all.
That would like forcing a PC to pay 20 gold b/c some npc merchant succeeded at a skill check.
Again, why would that be a bad thing? Isn't it appropriate that naive sucker PCs behave like naive suckers?
What about if we were talking pickpocketing instead, should PCs be immune to that?
What about an NPC beating a PC with a Befuddle Check vs. a hostile wizard NPC casting Paralyse on a PC vs. a hostile gladiator catching a PC in a net?
From where I sit, treating PCs differently in one situation is to introduce jarring inconsistency for the sake of... Well, I have no idea.
Do you even fukkin' know what skill checks are supposed to represent. Read. the fukkin. manual.
I suspect you meant to ask something else, but yes. The check represents everything that can go right and wrong during the use of a skill. Major elements typically take the form of fixed values, while minor and rare elements are typically represented by a dice roll. The combined result is used to determine which of a number of possible outcomes has occurred. Of course, this is the basic concept. Individual RPGs run in all sorts of directions with it.
Considering I don't play D&D and never intend to, I think my knowledge of the various editions of the system is pretty impressive. And I don't think it's the least bit unreasonable of me not to want to read any D&D manuals. More, I fail to see how D&D is any more or less relevant to discussions of Project Eternity's social skill mechanics than every other TTRPG system under the Sun.