I think this may in fact be a source of dissonance that you and I have in some of these conversations, particularly where it pertains to The Forge and, more specifically, "system matters."
I get plenty of dissonance from The Forge. I mean, if the Forge were trying to tell you "roll a d20, you want high," it would take 12000 words, and /none/ of those words would in any way refer to dice, the number of faces on them, nor the target for success - but, they'd sum it up in a completely nonsensical label at the end, so Forgites could say, IDK, "Confirm Brisance" when they mean "roll d20 you want high," and then link you to the 12k word Ron Edwards opus that fails to explain that's what it means.
(And, no, I'm not going to tell you how I really feel, I'm going to enjoy my 4-day weekend.)
The most fundamental core mechanic of VtM and White Wolf games is "The Golden Rule" or "there are no rules" or, apropos, "system doesn't matter."
The Wolfie no-rule is hardly a /mechanic/, but sure, more or less. They also famously said "Bad rules make good games!" so it's not that system doesn't matter, it's that systems should suck, to /force/ the GMs to override them and the players to angle for that as much as possible.
pemerton is referring to AD&D 2e above (surely), not 1e.
While 1e wasn't /trying/ to be a system so bad that playing it would train everyone to accept and rely on the DM's judgement & ultimate authority, it still prettymuch got there.
AD&D 2e went all-in on this ethos. CoC does as well.
It's the height of irony that anyone would conclude that AD&D 2e and Storyteller have anything in common. They fought their own bitter precursor to the edition war, the ROLL v ROLE debate, through much of the 90s, on the basis that they were absolute polar opposites, with D&D the deformed poster child for all-rules-all-the-time ROLLplaying and Storyteller the glorious paragon of ROLEplaying, GHoD* Complex notwithstanding.
Not that D&D and Storyteller don't both throw everything at the feet of the DM and demand he fix it, but just that's it's the freak'n Height of Irony.
CoC (and BRP in general), though, not see'n it s'much. % skills, not so weird nor requiring of constant intervention as all that. And, as questionable as much of 2e was, it was less incoherent (in the English meaning of the word, not the Forgelish) than 1e.
The lifeblood of those three gaming systems are overwhelmingly GM Force and opacity, inadequacy, incoherency, or impotency of action resolutions mechanics (which, not coincidentally force multiplies the "heavy GM mediation/Force is required to make this game work" angle), where GM latitude is at its utter apex (in all the history of TTRPGs) and subordination or outright ignoring action resolution mechanics/outcomes so the GM can curate the play experience at their discretion is the most fundamental aspect and energy of play.
With the exception of articles and conjunctions, I'm guessing not one word of that actually means what it sounds like it means. Because Forge.
Quite literally, those 3 systems probably have more to do with why The Forge was created than anything else.
I'll /try/ not to hold it against them.
* Great Handfuls of Dice. In some storyteller games you could get really large dice pools together, and if you could twink** out a low difficulty somehow, an egregious number of successes. But, apparently, the GM was supposed to ignore the 17 HL you just did to the 8-HL target who only soaked 5, and just narrate it the same as if you'd hit him with a feather duster.
** Yeah, I wondered about that, too, first time I heard it but, no, different meaning: for some unknowable reason the Storyteller community in the 90s used 'twinky' or 'twink' as either verb or now when talking about muchnkins, powergaming and what would come to be known more politely as system mastery.