Dead is real only when the story says so
Except the story does say so. Especially with our mage companion who ends up in the afterlife essentially.
We are dead dead until revived, the KO mechanic exists for dead but not dead yet reasons.
The resurrection via 200gp, which yeah is insanely cheap. More so since there are no copper or silver coins. Seems to be based on the fact that you are dead story wise.
Same counts for companions who aren't members of the party, like Wyll who died 2/3 playthroughs at the gate before he even joined my party. So he ceased to exist as a character right then and there.
I'm not really mixing story and mechanics up. Just a pretty logical extrapolation.
The problem with the shotgun to the brain analogy to remove cancer is that well... if you're brought back you'd still have it. While the tadpole leaves a dead body because it doesn't want to be in a corpse nor can it survive like that. Hence why it escapes even in game in a cutscene.
In universe, this is a perfectly reasonable thing to do considering you don't know when you'll end up a mindflayer. Would you really take the chance of going out on a wild goose chase that might not net you a cure when you can just... do it literally right then and there and the worst thing you get is wasted coin? Or a scroll?
It is super low risk. More so if they just ask not to be brought back to life if they fall in battle, to see if the tadpole really would leave. Which by all logic and lore it should.
Yeah, its purely a plot contrivance that this isn't a solution. But that makes me wonder if that means the plot, or such easy access to resurrection, was a good idea for the FR setting. Personally I can see why it's like this from a game mechanic but that doesn't fully excuse the plothole. Since it just seems odd setting a story in a setting but having it be rather contrived to even work. It's not a big thing, or a major thing. It's just a bad thing that is. And only exists due to ease of access to resurrection within the very start. I know it'll be rarer afterwards but even with 200gp price that's pretty cheap and easy to access. And is still a cure you can work towards by proxy of tadpoles bailing out.
Which is kinda great since this is really the only issue I have with the game. It's really good besides, with well made quests (in structure ignoring any EA issues), interesting stories, great interactions etc etc. Overall its a great experience with little to complain about. At the very least for me. I'm not huge on DnD or FR stuff. But this just stood out to me.