I mean to say that if you can write and are unable to express your ideas, you probably won't be able to do so verbally either.

In the case of kids, of course, that's true, but just because they can't write.

But if you can (and most people can) just having the option of voice input won't help.

I refrain to take a stance about how much of the population is unable to articulate thoughts in writing, (it's probably not great though) but it's probably going to be comparable with how many can't express themselves verbally as well.

I'm talking here about more complex ideas of course. I'm sure average communication is functional.

Plus the LLM could adapt its language and dialect to say Appalachia or Compton, etc.

I am surprised about the amount of resistance this is getting. Yes, some people talk more than they write. Yes, some people can't write but they can talk. But, that's just the environment the words travel through. The words themselves, they will be the same. I conceptualize expressing in writing as more lenient than communicating verbally. Verbal communication leaves much less time to ponder your ideas and pick your words carefully, thus, it's harder. I maintain my stance, if you can put words to paper (and the vast majority of people in the first world can do that) but are unable to communicate your ideas this way, you probably will fail doing so verbally as well.

If my supposition (Speculation? Stronger than it should assertion?) Is true then just interpreting requests verbally will not help

Yup, poster seems to be completely ignorant of pre-written word civilizations which used oral means to transfer knowledge through successive generations for millennia.