I wish they would elaborate a bit more on each single point. I'm quite happy about docker, so I'm especially interested when someone has a negative opinion about it. But here I feel like there's no meat to this article.
It's kinda badly described and unintuitive. The amount of people who were surprised by the firewall rules messing up their existing firewall setup is very high. And it also just grabs a subnet and you have to dig why it would use that one and not another. Not sure about conflicts. But it's a bit of "it works until it doesn't".
I didn't have many "wtf just happened?" moments with docker, but 100% of them were network-related and half of them were hard to troubleshoot.
While I agree that developers should support and have documentation for hosting without Docker, I think the arguments in the article are very poor.
It's completely fine to dislike a technology - hell if I don't! - but here it seems like they are arguing against Docker just for the sake of it.