The only exception I can think of to this rule is for highly visual medium like graphic novels. In this case, typesetting and layout are inseparable from the medium. That being said, I don't think Medium is designed for that type of use case
There may be other cases where creative choices in typesetting and layout may enhance the writing, but this usually isn't the case. Normally, when an author tries to "spice up" their writing this way it ends up looking like a crappy MySpace or GeoCities page.
As an aside, George RR Martin apparently uses WordStar 4.0 to write his books. I don't know if this proves or disproves the argument. Maybe if he had more control over the typesetting and layout, he would be done with Winds of Winter by now.