It's a running theme with a lot of these quest-lines. "Let's ignore common sense in regards to the player, and the items that exist in the world that can change the fate of their friends."
Nox Mirrorhelm you can find? You can't use it to save Blaidd. The unalloyed gold needle? There is no way to bring Malenia to Farum Azula to use it on her.
Only characters that are allowed to have a happy ending are like Boc, and even then, he also has a really bad ending where he just dies and is stuck reincarnating and dying endlessly if you're not nice to him.
You can also save Rya and Big Boggart. By refusing to kill Rya and refusing to give her the tonic. Which allows her to finally move on from the Volcano Manor, and live her life outside of it. You save Big Boggart by just murdering the LOATHSOME DUNG EATER immediately. And why wouldn't you the guy literally rapes corpses.
Big Boggart is my man. Shellfish Stans Staying Strong.