I think you're being overly dismissive when it comes to easy dev environments. I was recently fixing the reddit vagrant environment and it was absolutely excruciating:

- Creating a scratch VM (not even provisioning) is a speed bump when you want to re-running scripts on a pristine environment to validate them. Starting a Docker image takes ~1s.

- Provisioning is slow! Reddit suggests installing a plugin (vagrant-cachier) to keep you sane. I ended up downloading a plugin to take VirtualBox snapshots of my VM and even that was depressingly slow. Docker commit takes maybe 20s on a big layer.

- VirtualBox shared folders are pretty bad, so apparently I should install vagrant-bindfs (and NFS packages). -v is effectively zero effort.

- I had to keep on shutting down and starting up the VM to tweak memory settings - too big and my laptop died, too small and nothing would start. You get far more flexible controls in Docker.

I couldn't help but think all the way through that putting everything in a Docker container would just be a far nicer experience, even if it does violate the single process rule - for this use case, Docker solves some papercuts very effectively.