Ruin Explorer
Legend
It seems like you're defining swingy pretty weirdly from my perspective.It depends what you mean by "swingy". D&D rolls are almost all on a pass-fail scale with no real escalating network of consequences. Anything PbtA, by contrast, has actual swings from any roll and something happens on a miss. The range of possible outcomes in PbtA is vastly greater than D&D ever gives. And I haven't played Cortex Prime or even delved into it but the hitch and botch system.
Basically if you need a 7 or higher to pass in D&D there's no difference between a 1 and a 6 on the dice or between a 7 and a 19 (and generally not between a 7 and a 20). There are only two possible outcomes and they're both pretty basic.
I would define it as any system where the rolls have both a very flat distribution and a sizeable chance of outright failure. D&D having a purely pass/fail system magnifies the swinginess, as does it using a d20. It's got nothing to do with the "range of outcomes" (or rather I don't see how it could). You can have an absolutely vast range of outcomes without being at all swingy, if there's a large chance of the main outcome and the outlier ones are progressively further away from that instead of abruptly dropping off. Something happening on a miss doesn't increase the swing factor.
If we define it the way you seem to be doing, that seems to be at odds with the OP's suggestion that D&D is swingy, which is weird to me, because D&D (and relatives) is the game I most often see really wacky/silly results coming up in, purely due to dice rolls. It's also the game with the most wasted-feeling and empty-feeling rolls, many of which simply serve to nullify other effects.
I don't know what the hitch and botch system is - it's not present in Cortex Prime, or not called that.