Virtual machines are cumbersome and heavy weight compared to Docker for specific solutions like say Plex, NextCloud, and others. Recently I (and others) have encountered issues on NextCloud getting Collabra Online to work - this is due to our environments being different from the "ideal". With Docker, you can quickly install the "ideal" image and eliminate those problems, along with using less space and resources.
Upgrades can also be easier as the image itself usually updates - from one "ideal" to the next version "ideal". Right now my Drupal installation has this problem and is failing to complete its upgrade. If I'd used Docker it would have gone a lot better...
It's just a question of getting familiar with what Docker is and what its context is with regard to using it. I'm getting into it now so that I can easily use Docker images within my new NAS I'm building.
See What Is Docker? | What Is Docker And How It Works? | Docker Tutorial For Beginners | Simplilearn
This Docker tutorial will help you understand DevOps tools, what is Docker, how does a Docker work and components of Docker. Docker is a tool which is used t...