Docker is not a silver bullet, and it is definitely being over-hyped right now. But it does have some great usage cases, and it has got a lot of people working together on re-thinking how we build and deploy applications. I think you'd be more likely to bring about positive change by adjusting tone and trying to point out some usage cases where Docker excels. I can't speak for everyone else, but I'm a lot more likely to take someone to heart who shows some balance while criticizing.
Unless you just wanted to get lots of page views with an hyper-critical (though well-researched) article. If that is the case, carry on and disregard this.
However you're quite right to point out that this article fails to represent the positive impact of the Docker ecosystem, something which several other people have also commented. I'm going to amend the article to reflect this.
[1]: https://groups.google.com/d/msg/django-users/5xIYUrEFfUs/KAI...
I feel like if you're going to criticize running your own registry you really need to devote more time to it. You can get an S3-backed, distributed private registry running in about 5 minutes using their provided image. It's really, really easy.