Maybe easier to get anything runnin quickly. But it obfuscates a lot of things and creates additional layer of stuff which you need to then manage. Like few days ago there was discussion about how docker, by default, creates rules which bypass the “normal” INPUT rules on many (most?) implementations. And backup scenario is different, it’s not as straightforward to change configuration than with traditional daemon and it’s even more likely to accidentally delete your data as a whole.

As I already said, docker has its uses, but when you’re messing around and learning a new system you first need to learn how to manage the ropes with docker and only after that you can mess around with the actual thing you’re interested of. And also what I personally don’t really like is the mindset that you can just throw something on a docker and leave it running without any concern which is often promoted with ‘quickstart’-type documentation.