It can be, yes. One of the largest complaints with Docker is that you often end up running the same dependencies a dozen times, because each of your dozen containers uses them. But the trade-off is that you can run a dozen different versions of those dependencies, because each image shipped with the specific version they needed.
Of course, the big issue with running a dozen different versions of dependencies is that it makes security a nightmare. You’re not just tracking exploits for the most recent version of what you have installed. Many images end up shipping with out-of-date dependencies, which can absolutely be a security risk under certain circumstances. In most cases the risk is mitigated by the fact that the services are isolated and don’t really interact with the rest of the computer. But it’s at least something to keep in mind.
Yup. For minor issues, first aid is all that is needed; you don’t need to see a doctor for a minor cut, as long as the first aid ensures it’s not infected. But for larger things, secondary aid is what provides more long-term recovery.
If someone dislocates a shoulder, first aid is putting it in a sling and bracing it against the body, so it doesn’t get worse (for instance, the tendons and ligaments in the shoulder joint can tear) before they can get to a hospital.
If someone is massively bleeding, first aid is stopping the bleeding to keep them alive until they can get rescued.