There are configuration and package management systems (e.g. Salt or Ansible and apt or pip). Containers provide that + isolation, but I bet for majority cases

There are configuration and package management systems (e.g. Salt or Ansible and apt or pip). Containers provide that + isolation, but I bet for majority cases no one cares if two services are walled from each other or not - as long as they don't interfere. Usually, they rarely do - and when it happens (say, an ancient blob wants an older libc), in most of cases a mere chroot does the trick, without need for cgroups/namespaces/extras.