The counter argument is some people are terrible at writing. Millions of people sit at the bottom of any given bell curve.

I’d never trust a summery from a current generation LLM for something as critical as my inbox. Some hypothetical drastically improved future AI, sure.

For the case of writing emails, I tend to agree though I think creative writing is an exception. Pairing with an LLM really helps overcome the blank page / writer's block problem because it's often easier to identify what you don't want and then revise all the flaws you see.

On that topic I’m the founder of inbox zero: https://getinboxzero.com

May help you get half way there

  instructing an agent to write anything from scratch inevitably takes more time than writing it yourself

But you can reuse your instructions with zero additional effort. I have some instructions that I wrote for a 'Project' in Claude (and now a 'Gem' in Gemini). The instructions give writing guidelines for a children's article about a topic. So I just write 'write an article about cross-pollination' and a minute later I have an article I can hand to my son.

Even if I had the subject matter knowledge, it would take me much longer to write an article with the type of style and examples that I want.

(Because you said 'from scratch', I deliberately didn't choose an example that used web search or tools.)