I have, in the recent past, done multiple coding interviews. Thus far none of them have been useful to me, and none of them have provided information the interviewers couldn't have gotten already from my GitHub contributions. The single personal anecdote was meant to reinforce my points: from that interviewer's perspective there's a good chance that I'll be one of those "people who can't write code" who forms the basis of later stories about how great it is to use coding interviews as a filter.
Meanwhile, I do go into some detail about the issues with coding interviews in general, and the way they can affect and accidentally weed out candidates a company probably didn't want to weed out that way.
Also, the "nobody can really code, you have to do this to filter them" thing is approaching cargo-cult status at this point. Further up in the section on education I touched on some reasons why I think those situations happen.