Although I agree this approach is absolutely flawed, and anyone doing so needs to re-evaluate their workflow, I feel this comment is more an argument of doing things properly, rather than a positive of Docker. Everything you mentioned above can be easily achieved by using Vagrant and a provisioner. But as discussed in other comments, the Docker ecosystem helps you get started quicker.
You seem to assume that everyone should be doing everything the "right way". Turns out they don't. I found it easier to deal with stuff not being done "perfectly" than to try and argue other developers into doing stuff "right".
As opposed to those who prefer imprecise, flawed and ugly solutions? Jesus dude, could you possibly come up with a more arrogant sentence?
Have you ever looked at the source code of a dependant library, followed by an overpowering and compelling urge to write your own from scratch? Suppressing the urge to rage quit because your tools are fighting against you, not with you. For me, it is a constant daily fight to force myself not to do things "properly", for it's mostly an unrealistic and unachievable goal.
Believe me when I say that being a perfectionist is nothing to be arrogant about, and despite it being one of my major strengths in some ways, it's also one of my biggest flaws.
(I'm taking it on faith that you're not trolling, and have taken time to give an honest reply)