Yeah, veekie's trackin' on this one.
Once the contract has been established,
everyone is beholden to it --
including the DM. If someone is violating the contract, then they are breaking the trust and need to be called on it. If that violator happens to be the DM, and he does that often enough, then sure, he doesn't deserve to have a group for which to DM.
Let's look at the second link I posted (as an example):
Personally, I generally prefer the "Collective" play style; however, I'm fairly comfortable with "Competitive-Collective", and can go with it if that's what the rest of the group prefers. OTOH, "Individualist" is generally a non-starter for me. So, if I decide to sit down with a group that operates under the "Individualist" play style, then I have no one to blame but myself if I'm not having any fun --
I've broken the contract, even though it's me that thinks that
they're "doing it wrong" (they're not doing it wrong, because I'm the one who broke the contract) -- and so it's up to me to either "get on board" or find another group.
Another big piece of the social contract (probably one of the biggest - if not
the biggest - pieces) is that of how
Authority is expected to be shared. Putting this in a codified format and then letting it stand as it's own entity can go a long way in settling these types of disputes.
Regardless of which side of the screen you're on, you all are still a group -- as such, if the contract is being broken, then any/all at the table should have equal right/responsibility to invoke the contract when something goes awry.
That being said, the structure of D&D seemingly necessitates the idea that the weight of someones words should be some function of their in-game creative control
as per the agreed-upon system(s).
All that being said .... once a social contract (or any element thereof) has been established, and I decide that I'm going to DM a game under
that contract, then yes, I (definitionally) expect any/all players at my table to follow that contract (just as I expect
them to hold
me to the same).