Faolyn
(she/her)
In GURPS, many disadvantages have control ratings, which you have to roll under in order to resist succumbing to the disadvantage. For instance, Addition (9) means you have to roll under a 9 on 3d6 to avoid having to give in and use the substance, while Addiction (15) means you have to roll under a 15. Obviously, a control rating of 9 means you're far more likely to succumb to the addiction and as a result, is worth more points than taking the same disad with a control rating of 15. Other disadvantages, such as Vow, lack control ratings; you either follow them or you don't, and if you don't, you suffer whatever consequences are listed in the disad's description.So why is it okay to have rules which tell you your character just dies, but not okay to have rules which (say) tell you your character thoughtthey knew what they were doing better than they actually did? Both of those are entirely real-world events, and the latter is (thankfully!) much more common than the former.
Why is it okay to have rules which tell you your character flubbed their attempt to convince a shopkeeper to cut them a deal, but not okay to have rules which tell you your character flubbed their attempt to adhere to their (entirely mundane) oath against consuming intoxicants?
Why is it okay to have rules which tell you that your character's ability to tell if someone lied to them failed when they really needed it, but not okay to have rules which tell you that your character's courage failed when they really needed it?
All of these situations seem to follow the same exact logic, but the former is somehow acceptable because...it was what games did in the past, while the latter is unacceptable because past games didn't? I don't see why "when in Earth history this mechanic first appeared" makes any difference in the degree or nature of agency loss to these mechanics.
But here's the thing: The player chose to take that disadvantage. They specifically made their character to be an addict or decided that their character had sworn a vow.
In the rare occasion that someone gets a disadvantage after character creation, it's nearly always because the player chose to act in a way that caused their character to gain that disadvantage. They chose to take the drug or swear a vow. There might be a roll to see if the character actually becomes addicted (I can't remember what GURPS does), but the actual choice was up to the player. (And the few times the player didn't choose it, I'd wager most of the time it's due to an unusual outside influence, like a curse, which can eventually be broken.)
If a GURPS GM were to have the bad guy tie the PC down, force-feed them drugs, and then force the PC to take the Addiction disadvantage, and the player wasn't OK with that chain of events occurring, people would consider that person to be a bad GM and would be telling the player(s) to kick the GM out of the group.
Consent is important.
If you tell the player that their courage failed them and it's not because of an unusual outside influence that can be ended or fought against, then you are forcing them to act in a specific way without their consent.
(In D&D, nearly every event that would give you the frightened condition is due to an unusual outside influence--magic, poison, or being exposed to an otherworldly creature. And they all require you to fail a saving throw to succumb, and most of them allow you to make new saves periodically to end the condition early. No purely mundane events from mundane beings cause a character to take the frightened condition. However, a player can still choose to act frightened because of a mundane event or being, however.)
If you are choosing to play a game where your character can be made to act in certain ways without your consent, and you're OK with that, then go ahead. Have fun. But understand that for many of us, that is Not OK. And understand that for many of us, a game that's supposed to be about player-driven stories but doesn't allow for actual player agency is very, very weird and even hypocritical.