Honestly security is not the main reason I use containers, but ease of use. Docker (or containerization in general) makes it really easy to keep a clean host system when you regularly try out new services, there’s no baggage left behind when you remove a container and once you remove their mount/volume, you are usually rid of them pretty cleanly. Additionally it makes migration to new machines/distros way easier and less time consuming.

I don’t rely on docker seperation to keep my machine safe, although I probably could