Seems much harder to learn how to write how you never write, versus just learning to speak to a computer the same way you speak to anything else.
A lot of people on the autism spectrum can have issues with speaking or speaking speed, but have no such barrier necessarily to typing speed.
I'd imagine there's a statistically large number of people that meet that criteria on this website.
What do you mean how you never write? You can just write what for want to say instead of saying it out loud. It is not a special skill, it's no different than how you write a message, just that you don't hit backspace to go back and correct things.