Is there a meaningful distinction to be made between the system and the content?

[HidesHisEyes]

(Honest question, never really having delved into it): But would it work for a comedy game? One where the "action" component is basically background? Or a cosmic-level (like Exalted) game? From what I understand, it's fairly "grounded" and low power, and assumes that most of what you're doing is "adventuring".

It’s not necessarily low power - a wizard in Dungeon World can do literally anything with magic, if they fulfil some stipulations from the GM. Druids turn into animals, fighters can guarantee someone lives or dies in a fight. But it does assume adventures on the scale of mortals, yes. And it can certainly be comedic but the action is going to be front and centre and pretty relentless if you play it as intended.

So you’re mostly right about it, I just wanted to get across that it’s not at all some sort of gritty, OSR-style survival dungeon crawler. It can spin out in all sorts of directions.

D&D isn't generic. D&D is constrained in genre (and that genre is not "all fantasy"). It explicitly does D&D worlds, not "any fantasy world"--it's not an emulator, nor is it trying to be one. Maybe to make the difference, D&D should get moved up the scale to the 30s, with PF being removed from 40 as an example and being lumped in with D&D. Maybe (?) replace it with Starfinder, which is more setting tied. I think.

Agree D&D should be higher. It really isn’t generic.

It's worth noting that the 'death-is-easy' feel of GURPS is a product of the system that GURPS uses rather than any sort of tonal choice on the part of Steve Jackson games. It has to do with how the model system that is GURPS functions and unless you distort the numbers massively beyond all expectations it will always be that way. It is a solid example of how the mathematical model that 'the system' actually is constrain game options on a purely mechanical level.

A TTRPG system is ultimately a set of mathematical models (often bad ones), and the structure of those models constrains the possible permutations of the game, including through such things as the choice of dice to use, since different RNG setups produce different output curves. Ultimately any time you use any mathematical system at all this introduces constraints on the content of some kind.

You’re right but it can still be a deliberate tonal choice. No idea if it was or wasn’t with GURPS but it certainly can be. RPG designers don’t just pick a dice mechanic that they think models reality, physics and so on and hope for the best. They have other concerns in mind too, and that might include things like tone, appropriateness to setting etc. PbtA uses 2d6 and makes the 7-9 range, the most likely range, “success with complications” because that’s what we see most often in action packed and dramatic fiction: characters get what they want but in complicated ways.