TO EVERYONE DISAGREEING WITH THE PREMISE THAT WIN CONS EXIST IN TTRPGS
I want to throw several things at you so we can collectively evaluate your/our thinking on this. Ready? Go:
1) My Life With Master - At the final conflict with the Master, your Minion has attained Love (a currency that accrues, or doesn't, in the course of play; through the series of conflicts that make up the game, you've established relationships with the Townsfolk that have effectively awakened your character and allowed them to surmount their worse inclinations/disposition) greater than your combined Fear + Weariness (same). Maybe other PCs haven't maybe they all have? Maybe you're the only Minion that has done this?
Now the Endgame conflict with the Master is enabled and we cut right to the action to find out if you depose/kill the Master/Mistress or not. Anyone whose Love > Fear + Weariness is in the conflict. This_is_not_easy.
Is getting to this endgame conflict a Win Con?
Is getting to it and then defeating the Master/Mistress a Win Con?
Win Condition 1 -- get to endgame
Win Condition 2 -- complete endgame by defeating Master
I see these very clearly, and these are large WCs, because the game it entirely bent towards asking these two questions.
2) D&D 4e - You've authored a Major Quest for your character in the Heroic Tier of play; "Open the Gates of Man and Watch the Horde Pass Freely Through." It turns out that, in the course of the Heroic Tier of play, we all discover that this isn't a tangible thing. Its intangible. At the end of the Heroic Tier, you've won enough conflicts to have many allies in the Points of Light setting at your back when you confront "The Keeper." This is an upleveled (Level +3) Social Skill Challenge and you have to stake all the hearts and minds that you've won in order to convince The Keeper. Your Skill Challenge is a success. You open the heart of The Keeper who in turn opens the Gates of Man. The last scene of the Heroic Tier is watching the Horde pass freely through the gates.
Quest completed. If the group plays Paragon Tier (they may not...this may be a wrap), it starts from here.
If that's a wrap, Win Con?
If that's not a wrap and this Major Quest profoundly shapes Paragon Tier play (while of course establishing a significant amount about the setting and your character), Win Con?
Win Con either way?
WC1 -- complete the major quest
WC1a -- understand quest objective
WC1b -- gain sufficient allies to have enough resources to address WC1
WC1c -- define conflict for WC1 in a way that's surmountable given WC1a and WC1b.
Yup, I see these laying out this way. WC1 is dependent on the sub conditions being fulfilled to be completed. Again, major question of play is being addressed here.
3) Aliens RPG - You're a Scientist for Weyland-Yutani. Below is your Agenda.f
PERSONAL AGENDA: That Weyland-Yutani inspection team won’t be so snooty if you can leapfrog them and get an alien to the Company first. You just need to get a live specimen and get off LV-426 alive. Who will be laughing then?
You successfully commander the evac and get a live specimen and yourself off LV-426. The final scene is you entering cryostasis as The Mother plots the course for your destination.
Win Con?
Oh, clearly.
4) Dogs in the Vineyard - Your backstory initiation scene (the situation is player-authored and the GM plays the antagonism/obstacle) involved you getting picked on (again) and your goal for the scene is "I won't let my temper get the best of me so that I end up beating yet another initiate into an inch of their life." You fail and therefore gain the 1d6 Trait "I can't lick this awful temper." When you deploy it in conflicts its apt to help you when you can use it, but its certainly a much better chance to earn you Fallout than a d8 or d10.
In the course of play, you lose some conflicts and therefore take Fallout. You throttle back that d6 Trait to a d4 which makes it a significantly complicating feature of your life. When you deploy it, it will help you because you've got an increased dice pool, but you're more apt to get Fallout (negative affects to your character that affect them thematically and their attendant PC build structure). Now your Temper is really causing you problems.
In a conflict in a Town, you're able to use that Trait in a social conflict, not escalate to violence, and win the social conflict (you get what you want without having to go to fists/knives/guns). Between Towns is Reflection. That Trait goes back to d6 because it helped you.
Rince, repeat in another Town. Now its a d8 (a major asset).
Win Con? No? Ok...
Rince, repeat another Town. Now its a d10.
You've mastered your temper and its an asset to your life as a Dog.
Win Con now?
So, this one I like because it's complex and not the direct focus of play like the ones before. Here I see the Win Con as clearly established up front, with the statement "I won't let my temper get the best of me..." This seems the question, and hence win condition, of the entire example -- we're seeing if the character wins or the temper wins. And it goes back and forth. The character loses this win condition, then loses it again, then, slowly, starts to win it. It iterates, each new session being another iteration of the win condition, another new test of it. And, at the end, it's still not fully answered, just that iteration of it is clearly and unambiguously a win -- the character has the best of their temper in that moment.
5) Dungeon World - Its the End of Session move, you've got the following Alignment; Save an innocent from the cruelties of man. You've got a Bond with your Wizard companion; I'll show Mork that kindness pays off. You rescue a fox cub who was down a well project that was abandoned by prospectors. The cub is near death due to exposure and dehydration, etc. You win the conflict to get it out of the well and then you win the conflict to restore its vitality. You now have a Fox cub Cohort (with some kind of move/Skill that helps you due to love). You also learn something new and interesting about the world; There is a prospecting group that is ravaging the countryside and throwing salt-of-the-earth folk off their land for a pittance of a return (and this triggers a new Bond or Alignment statement).
You mark xp for Alignment and Bond and Learn Something New About the World at End of Session. Mork's player changes their alignment from Neutral to Good.
Win Con?
Maybe you level up from those 3 exactly. Win Con?
Yup, I see these as clear win conditions. Nice, again, that these are about overall play, but rather smaller moments in play that address only a part of the entire play for a session. These smaller goals, and how XP is awarded to them, is a nice example of how different systems encode this kinds of win conditions in ways that are pretty different to D&D. It also opens up the understanding of how you can get these "wins" at this smaller, iterative resolution and how they build up play and shape it in clear ways. Ways that are generally opaque in D&D because of how that system operates.
6) Blades in the Dark - You're possessed by your friend's Demon Rival due to a Consequence of the Score prior. This only manifests intermittently (a Fortune Roll based on the Magnitude of the Demon; 3d6 so if a 6 shows up when you make an Action Roll, the GM is taking over and afflicting a Desperate Consequence on the Crew).
The Demon manifests horrifically in the subsequent Occult Score; a ritual to adjure the Demon. Its likely to kill your friend (its Rival). You determine that the only way to save your friend is to throw yourself into the Spirit Well that is being used as the nexus for the ritual (thereby destroying both you, your spirit, and the Demon). You succeed at the Action Roll.
You cast your character into the spirit well after you momentarily regain your normal visage from the Demon in order to glance at your friends with a smile of "its ok...I've got this." You're over the lip and gone...the Demon with you.
Basically like The Exorcist.
You're making a new character or you're changing one of the Crew's Cohorts to become a full fledged PC.
Win Con?
Oh, gods, no. Cults are the worst crews, they're Blades on Hard Mode, and there's no winning at all. At least, that's what I've been lead to believe.
/inside joke
Yeah, no, especially since I'm aware of some of the particulars of that game (not a player in it, just have some insight into it), that's absolutely a win condition for that game. Desperately needed, in fact.