As a Dyslexic myself I kind of get and agree with a lot of what you say. I especially miss the spell checking etc.. (for example I just had to correct four words after typing that sentence.. and two in these brackets)
I have tried to write it out in an editor then cut and paste it.. but you know what, someone has already replied again and ruined what you just wrote.
There are also other issues with Dyslexia, like the scrolling of text, and missing out some replies. We are known to loose our place when reading pages of text, and scrolling chat is worse.
Also Dyslexics see the world a bit differently, so arguing with us is not easy. Others will have something specific and Dyslexics will have seventeen possible positions they are considering.
All in all text chat is not a great way to communicate and we add extra noise into that through culture and disabilities.
So not wanting to pull this too off topic.. Yay for dyslexics, at least we get special powres