(Note: it is not downvoted as I write this comment.)

First let me say that I have enjoyed kalla's recent contributions to this site, and hope that the following won't come across as negative. But to answer your question, I at least question both the uncontrovertiality and correctness of the summary, as well as the inference that more working memory increases abilities exponentially quickly. Kalla and I discussed some of this above and he doesn't think that his claims hinge on specific facts about working memory, so most of this is irrelevant at this point, but might answer your question.

EDIT: Also, by correctness I mainly mean that I think our (us being cognitive scientists) understanding of this issue is much less clear than kalla's post implies. His summary reflects my understanding of the current working theory, but I don't think the current working theory is generally expected to be correct.