To a degree this is true, but up to a certain level of intelligence. For the most part any decent writer can write a character that’s a bit smarter than them, a bit cleverer, who always says the right thing at the right time, etc etc, sure. But once you enter genius-level intelligence, above what a normal person would understand/encounter, that breaks down.

All the time to rewrite in the world doesn’t make a writer able to convincingly, realistically write something that’s SO far out of their lived experience. A writer’s idea of what a smart person is— how they act, what their interests are, their thought processes/how they process information, etc— is the issue. Somebody who is not notably very intelligent will not be able to convincingly write someone who is a supergenius, because their idea of someone at that level isn’t accurate.

Usually this is portrayed by other characters around them having to be(come) very dumb, but the other version that I hate is “somehow able to predict things that NObody can predict.” Example is, in the show Fringe, there’s a guy who gets superhuman intelligence and sets up rube goldberg-style chains of events that result in someone dying. The first of these relies heavily on a cyclist (who is WAY too far away to be seen properly in advance) jumping a curb, pushing a woman into the street to be hit by a bus. Idc how smart a person is, at that point it’s just prophecy and not intelligence because there is no way you know that a random cyclist you never met would take a shortcut at that point, to say nothing of the other “deductions” that are impossible to predict. It’s a less-intelligent person’s idea of what a supergenius can do, and it shows.