Imaro
Legend
This sounds like it's a bit of flavor and not much else. Kind of like the Traits, Bonds, Ideals, and Flaws of 5E D&D. It's there, and it potentially helps give a sense of character, but it doesn't influence play a lot, and usually only when the player would like it to.
And that's fine. I think some of us here in the discussion prefer when something like a character's flaw may actually be a flaw that causes trouble for them. I prefer that, I think. That can be achieved through some mechanical carrot, maybe offered by the GM or maybe suggested by the player....I think Fate does this, though my experience with that game is minimal. Blades in the Dark does it by simply offering XP if the PC struggles with their Vice or their Traumas; so it's still up to the player, but it offers them a whole new XP trigger that they can use to advance.
These kinds of mechanics make it so that the character traits of the characters are more central to play. They actually come up and matter, so that the game is actually about them.
Again, this is possible to do with something like D&D 5E's Traits and Flaws, but it will require a player who is wiling to work at it, and maybe some effort on the part of the DM make sure that it carries more weight.
I get that others may prefer something different, but at the same time if we are doing analysis then it's important not to leave a potential possibility out that might suit others better. Ultimately I just wanted to show another option, and one I would argue is popular enough that it should probably be mentioned as well.
I would also state that the flaw being established in this fashion does not preclude it from being central to play or from coming up and mattering. What it does do is push that determination solely onto the player who chose the flaw as opposed to enforcing it with game rules.