Seath
Why does Seath have a library of millions of books he can't even read? Yes, I know Gwyn made him duke or whatever (duke of what, exactly, dukes own land and collect taxes from it, he just has a tower that probably smells like body odor?), that's not the question. Why does Seath have a library at all? He's blind and he can't even traverse the passageways or use the stairs or use the elevator, he's too damn big to even open the books. And lets say somehow he CAN see and he CAN traverse the passageways and stairs and elevators, he still can't read, he's a dragon, he's illiterate. There is only 1 language across all 3 games, you see the script of said language in summon signs (lowkey looks like if Hebrew and Mandarin were in a blender) and all we've seen Seath do is scream so I'd assume that's ALL he can do and thus he's illiterate. Lets say he IS literate and is NOT blind, at his size could YOU read the print of a human-scale book? No.
The Duke's Archives is a fantastic area with a very cool cave at the end and a cool-looking easy boss, but it makes NO sense.