The lack of an efficient IME for verbose math input on a computer certainly accounts for why math is still terse when done in real-time such as when extemporaneous lectures or when working something out. But I don&#x27;t think it fully explains why the convention persists even in published works that took months or years to prepare; there&#x27;s got to be a significant effect for the readers and not just the writers. If a longhand style of presentation were as clearly superior for mathematics as for software source code, one probably would have caught on by now.