Re: Am I missing something ?
We already have grammar checkers built in to stuff things like Word up totally into American English.
While we're at it, they're not "grammar checkers". They're systems that apply a bunch of mostly-inappropriate heuristics, nearly all concerned with usage, mechanics, diction, and other things which are not grammar, to prose which has been mechanically chunked but not actually parsed.
Those things may help marginal writers massage prose into something closer to someone's idea of preferred form, but they are by no means a substitute for learning to write well.
And they have nothing whatsoever to do with the system described in this article. Really, I can't imagine how the OP thought they're at all relevant.