That is very true, I suppose a more accurate way to say it would be the playbook does not need to run as the root user, and can instead use the permissions of a regular user. This lets all the volume mounts be owned by your user, instead of root. I think it's still an important distinction to make though, since by not running the playbook as root, the playbook can't directly change any of your server's settings, and only has the access the user you're SSHing as has.

Yes, this playbook is intended to orchestrate an already set up environment. I know Ansible can easily install and set up docker (using something like the awesome https://github.com/geerlingguy/ansible-role-docker), but I decided against it (at least for now) for two main reasons: Firstly to avoid becoming the root user, and secondly to avoid the Ansible role installing a second version of Docker, causing things to break. I ran into that myself while testing this playbook, where I had set up a Ubuntu VM, told the installer to install Docker during setup not knowing it would install it through snap, then the Ansible playbook would install docker again through conventional means causing a lot of strange problems. So instead I opted to let the user install docker however they'd like and not have any gotchas like "Remember to add --skip-tags="docker" if you installed Docker during OS installation on Ubuntu" or uninstalling their version of docker for them