Some of the answers are interesting. I agree with you that most of the companies they mention on their page are so big that it makes you think that Docker is a thing for big companies, and not relevant to what I do.
For my part, I use Docker for my personal home server to keep dependencies documented and keep everything cleanly isolated.
Currently I have 8 images running, and more sitting around that I spin up as needed, running everything from a minecraft server, to AROS (an AmigaOS re-implementation) , haproxy, a dev-instance of my blog, a personal wiki, my dev environment (that I use to run screen and ssh into for when I want to edit stuff - it bind mounds a shared home directory, but means I don't mess up to host server with all kinds of packages I decide to install).
It's gotten to the point where the moment I find myself typing "apt-get install" I pause to consider whether I should just put it in a Dockerfile instead. After all, if this is a package I'll need once, for a single program, the Dockerfile does not take much longer to write, and it saves on the clutter.
I have a draft blog post about how I'm using it I keep meaning to post - probably after the weekend.
https://news.ycombinator.com/item?id=8324138
Some of the answers are interesting. I agree with you that most of the companies they mention on their page are so big that it makes you think that Docker is a thing for big companies, and not relevant to what I do.