If that’s the most notable thing you can remember from a “Batman” comic, then you’re not reading a Batman comic, you’re reading a New 52 Justice League Geoff Johns comic & pretending you’ve actually been reading the character’s proper stuff pre-52 when he’s a detective in Gotham City>>114124538
This but unironically. Not that it excuses anything Doom does, but he's not being delusional when he says Reed thinks he's smarter than everyone in the world despite Doom, Stark & Strange being capable of things Reed could never do. It's kinda of like when Lunella, Valeria, Cho or Pym squabble about how "I'm the smartest being on the planet" despite all of them never doing 1/10th of the things every other genius has done - it's insufferable because they're taking such an unquantifiable metric of "smartness" & trying to grade each other on it despite having contributed nothing as much as other people have - while Reed is there saying he's the smartest just because he is.
Doom can do literally anything he can imagine: building a machine to get to heaven, find a cure for The Thing, steal The Beyonder's power to become the 2nd most powerful being in creation. And Reed will still sit there in his flying Bathtub & claim he's the smarter of the two nonetheless. Imagine playing a game of chess against a chicken. No matter how skilfully you play, the chicken will step on the board, eat a pawn or two then strut-about thinking it's the winner. That's how Doom must feel about a chronic masturbatory bragger like Reed.
Doom is a psychopath, no doubt about it, but you can see why he doesn't like Mr Fantastic.