
That's not an ad hominem, that
is the most likely explanation.
I think your bias is showing. Like I said, in my experience, the better the roleplayer the less likely it is that they are going to get outraged by in system support for a character contract. That, as I admit, is my bias. Typically the good players look at the in system support, and think something lequivalent to, "Cool. I would have created and abided by an implicit or explicit character contract anyway, so this is in no way a burden." I just don't hear grumbling from people I've admired for thier ability to breathe life into a character concept.
In fact, in any case where player behavior is the problem, of course the players themselves have to be the first suspects, not the system.
Sure, but in my case I'm identifying the problematic behavior as being most associated with people who grumble about the alignment system. These are the 'jerkwads' as far as I'm concerned. (Well, not really, but it is your word so I'm using it.)
I think calling Sanity points for example a de facto alignment system is way outside the Pale. You can say that over and over again, but it doesn't make it any more convincing.
Fine. But I'm going to say it one more time, just because its so bloody obvious.
In CoC, I've never had a problem with a character wanting to play an outright evil character. Compared to horrors beyond man's imagining, what would be the point? The implicit table contract of the setting is usually, "We are all working to oppose the nightmarish horrors man was not meant to know."
But in the context of the game system, it is very reutine to have to undergo SAN checks when coming upon the aftermath or witnessing acts of depravity and cruelty. It's understood in the context of the game that acts of depravity and cruelty equal potential SAN loss. How much more so then could you expect to face SAN loss for actually performing acts of sadism and depravity? In fact, I could probably dig up a few cases in published scenarios where particular character choices lead to SAN loss as the logical consequence of the act (and incidently punishment for same).
But, let's invent an example for the moment. Suppose we have a scenario which amounts to the classic conundrum, "Which you burn down an orphanage full of children to prevent an unspeakable horror from being loosed on the world?" It would stand to reason that if the characters are forced to participate in burning a bunch of children alive, or choose to do so, that some amount of SAN loss would result precisely because we agree that the act has some absolute moral weight to it. Thus we see how CoC has a sane/insane alignment system (similar to Star Wars 'light side/dark side' system) which in many ways correlates to a good/evil alignment axis and which is strongly designed to enforce a particular mode of behavior, and incidently part of the reason why you probably see less 'kill things and take thier stuff' behavior than in D&D. I could certainly choose to play an insane cultist or psychopathic killer or someone that's lost touch with his basic humanity in CoC, but very quickly I'd turn into an NPC and would need a new character sheet. I can certainly choose to play someone with various 'shades of gray' but I better be careful I don't get too 'gray' or else SAN death spiral.
D&D's alignment system for the most part has no teeth, nor does it strongly encourage a particular mode of behavior. But it is quite easy to imagine introducing something like the SAN system to replace or enhance D&D's good/evil alignment axis (or heck, law/chaos if you prefer) and it would be immediately recognizable as an alignment system.
Then you might have a reasonable argument that the D&D alignment system was really that rigid.