To write more clearly, you don't need to dumb down or say less. Just get your thoughts into a logical order and express one after the other.
People who deliberately write unclearly because they think it will make them look smarter or give their argument greater authority.
In fact, my tweet was inspired by my own frustration: I'm writing something on a new topic, and finding it difficult to disentangle all the different points I want to make.
But that's what writing and editing is about.
Many students think they have clear ideas about a topic and are just bad at writing them down.
Nearly always, they actually have confused ideas—and learning to write better is their best hope of clarifying them.