My ds is dyslexic. At primary he really struggled with writing but we were told that he would probably catch up later and excel in things he was interested in. I didn't really believe them at the time, but he's 16 now and running an A average this year, in particular really enjoying critical appraisal.
Not sure why there is a belief that playing games means poor vocabulary. My son certainly talks a lot on line, way more than if he just talked to us. Last week he was busy arguing with someone about the relative differences between slaves in Aztec, Africa pre-colonial, Roman or pre-civil war America. I wouldn't say he was a very typical child, but gaming can be mind stretching and creative, or banal and violent, depending on the game and the child.
Anyway really my main comment on that blog is that ds at six is a very very different person to ds at 16. At 6 he woudl have a tantrum at being asked to read or write anything. Now he takes pride in writing, and does so very persuasively.