Spoilers for a 13 year old game that got retconned anyways
For those who don't know, at the end of Fallout 3 you have to go into a heavily irradiated room to prevent a big water purifier from exploding. Your character will die but your act of self-sacrifice gives everyone in the wasteland clean water which had been very rare up to that point. However it's been previously established (explicitly and several times) that supermutants are immune to radiation, and the game has a very prominent supermutant companion: Fawkes. You would think you could just ask Fawkes to go into the radiation chamber, but no, you get this incredibly stupid line and are forced to kill yourself. Fawkes up to this point has been very selfless and one of the kindest characters in the game.
Like how do you fuck up writing your game so badly this situation is even possible?!
Watch this shit. Ready?
Wow, it's that easy.
This is what happens when you write backward from the ending. New Vegas has several companions and one even gets you extra help in the final battle if you complete their personal quest. The other ones also just alter the ending slightly in general. They thought about how every quest and companion would affect the ending.
For Fallout 3 they wanted a specific ending, and then when they added things that could contradict that ending they just decided to ignore them because it's easier that way. They wrote in a heroic sacrifice involving a radiation chamber, then added in 3 companions that are also immune to radiation. Solution? Just make the companions not be there. Their solution? Make the companions all have some weird reason why they can't do it.
I like Fallout 3, and most of its "bad" design decisions are either justifiable on some level or not easily fixable, but this one is just baffling.