Good posts are good, and bad posts are bad. It doesn't really matter why they were written that way.
Anyone that usually writes good posts is welcome here. Anyone that usually writes bad posts is not. Again, it doesn't matter why.
The reason we don't like bad posts is because they degrade the site, dissipate volunteer effort, and turn people away due to high noise to signal ratio. None of those reasons change whether the poster just can't be bothered to write good posts, is deliberately trying to sabotage the site, is a troll, claims to have a disability, or actually has a disability. Again, it doesn't matter why.
So no, we shouldn't somehow "accommodate" those who write bad posts for some reasons, but not for others. We don't want to be in the disability police business, nor in the business of judging the level of disabilities.
If you have problems writing good posts, I see two options:<ol>
<li>Don't post.
<li>Get someone to help you make the posts good, <i>before</i> they are submitted here.
</ol>
Just as we don't care why a bad post is bad, we don't care what process was used to create a good post.
What we should be doing is rate-limiting or perhaps altogether banning those with significant negative rep, but that's for a different meta discussion.