I think the problem started far earlier. The author couldn't name a single clear rationale for using docker at all. One client asked them to, but why continue? They were using virtualenv and it mostly worked fine. So why docker period? Complexity for the sake of complexity? The rest of the article then basically says complex things are complex.
Well, I didn't name the reasons of why we continued using Docker because I thought they were obvious to any serious docker user. The reasons are all the promises that docker makes to you without actually telling you the complexities involved. Namely - the promise of better portability, better dev-prod environment replication (You can even run vagrant for dev portability but you wouldn't use it for prod, but with docker, its just docker everywhere), better scalability with managing clusters and deployments, and so on... without actually running heavy virtual machines. And no, as per the docker promise, it wasn't supposed to be complex.