[arisudesu]

If you run only the software you wrote, then yes, it is useful feature. Otherwise I won't trust automated pulls of whatever other devs put into their public images, nor won't I trust them for following image versioning properly and not introducing some addition in minor version that would automatically expose my files to the internet if not configured explicitly. There is too much trust I don't want to put in auto-updates.

As for the SystemD dependency, in this case the quadlets can not even be compared to docker-compose, nor be a replacement to it. Docker-compose always was independent of init system, where as quadlets are strictly tied to SystemD-based distros. E.g. users of Alpine, Gentoo won't be able to replace their compose stacks with quadlets.