This is one of the ways that moving the decision to the mechanics… to the gameplay… allows for player agency.
In the games of many folks here, I imagine that the player could make their climb check and get to the top whole and as quickly as possible… and the GM could then say “but you’re still too late… your friend has been killed”.
Keeping the roll so focused on success/failure of the task attempted rather than the resolution of the situation means that the GM gets to continue calling the shots.
Nice to see how you're always able to bring it back to "GM making any decisions = GM making all important decisions = bad play".
I didn’t say anything about it being bad play.
Do you really not see my point?
The point can be made more analytically, I think.
Let's suppose that there are three salient characters: H(ero), who is a player's character; V(illain), who is a GM-controlled character; and C(aptive), who is unconscious and/or immobilised and so unable to act. (And so at this stage I leave it open who normally controls C.)
And let's say the situation is this: there is an altar at the edge of a cliff, on which V has C restrained. V is going to sacrifice C at the "appointed time" (a pretty common trope). H knows this, and so does H's player. Through some-or-other game play, H has arrived at the base of the cliff, and now plans to climb to the top of it to rescue C. Given that this is H's plan, as formulated and stated by H's player, we can also take it that H's player, and H, believe that it is possible to climb the cliff before the appointed time arrives.
The GM tells H's player the difficulty for the climb (more on this below). H's player deploys whatever salient resources are available to them (eg drink their Potion of Climbing, or put on their one-use Gloves of Dexterity, or decide to use up their pouch of chalk dust, or whatever else might be applicable given their PC build, gear list, and the resolution system in question).
H's player rolls the dice, and succeeds! H makes it to the top of the cliff, and the GM now has to tell H's player what H finds at the top of the cliff. (NB. I want to set aside illusions and similar oddities that might lead the GM to describe things differently from how they really are. To make that easy to do so, I will stipulate that H is wearing Goggles of True Sight. Even without such a stipulation, the points I go on to make could be made; it would just require slightly more convoluted exposition.)
Let's say that the GM decides to tell H's player that H finds C dead on the altar. There are multiple possible explanations for making such a decision; but I want to take it for granted that, in making this decisions, the GM is following the heuristics, rules etc that they regard as applicable in these circumstances. Let's suppose that the GM has notes about the appointed time, has notes and calculations that yield the time at which H arrived at the base of the cliff, and has notes and/or calculations about the time required to climb the cliff; and when these are all put together, it follows that the appointed time arrived while H was (let's say) half way up the cliff. (Other possible explanations, heuristics etc are possible, I stick with this one just for ease of exposition.)
One question arises immediately: how does the speed of H's climb relate to the difficulty that the GM announced? Perhaps the GM didn't announce a difficulty, and just described the cliff (let's say, as a "challenging climb") - what was the framework in which the player made a choice about maximising the speed of H's ascent?
Let's further suppose that, as per the GM's notes and calculations, it was simply
not possible for H to get to the top of the cliff before the appointed time. Why was the roll still called for? At some point, based on notes and calculations, the GM
knew that H could not save C (eg perhaps when H arrives at the base of the cliff with no ability to fly or teleport). Why allow H's player to continue to hope, when the GM knows that the hope is futile?
In the scenario described, H's efforts in climbing turn out to be mere colour - they add content to the fiction, but they don't have any bearing upon the outcome that H's player cares about, namely, whether C is able to be rescued. That outcome was settled by the GM making their decision, based on their procedures, to which H's player was not party and was indeed ignorant of, given that H's player still hoped that H might rescue C.
I hope it is clear - it may not be clear, but I hope that it is - that a player might regard the scenario just described as frustrating, or even time-wasting. If all that is at stake is already lost, why are we at the table playing things out as if it's not?
Or let's put it another way: if the sort of scenario that I've described is taken as normal or appropriate or perhaps even, sometimes, desirable at a particular table, then to me it seems that
what is at stake is not a high priority at that table. The emotional investment in play must be going somewhere else.
The approach to adjudication that
@hawkeyefan has been pointing to, which takes the decision about whether or not the appointed time has arrived
out of the hands of the GM and places it
instead into the game play process in which both player and GM are participants, is a response to the possibility of the scenario just described. Instead of the GM being the one to decide what is at stake, and whether or not it is realised, the decision is "off-loaded" to the resolution mechanism. (Which is how D&D's combat system generally does things.)
There is also a (modest) connection to the other parallel discussion, about how to handle the passage of time. I think all RPGing involves telescoping time and space to some extent, due to the nature of the medium: eg we don't describe walking down a dungeon corridor centimetre by centimetre; when travelling on a hex map distances are frequently tracked in (multiples of) miles and time in (multiples of) hours; etc. Even with the climbing example, I've never heard of a RPG climb being resolved by a description of every bodily motion and every facet of the surface being climbed.
So, in the scenario I've set out, at what point does H's player come to know that time is of the essence? That's the point at which the key decisions start to be made - eg suppose that H sails to the base of the cliff in their trusty vessel, how long does
that take? And this is where, in an approach which aims to offload decision-making form the GM onto the mechanics, that that can begin. Eg if the player succeeds
well on the check for sailing, then they get a bonus to their roll to climb; if they do poorly, they get a penalty. (In the fiction, this reflects having more time, or less, in which to make the climb.)
To me, this is the actual point of "fail forward" and other techniques that relieve the GM of responsibility of deciding outcomes. It is about clarity as to what is at stake in the situations the GM is presenting to the players, and about the players' ability to win or lose at least roughly corresponding to the hopes that they form in response to those narrations. It eschews anti-climaxes that follow from "behind the scenes" GM decision-making that was outside the scope of player influence via the mechanisms of play.
At a table where there is little interest in stakes, (anti-)climax, etc - where success or failure at the climb is regarded as interesting even if the GM knew it to be ultimately futile all along - then these techniques will probably not be useful.
