Containers as a form of static linking means that you ship one thing to prod and it has everything you need locally in it and it can’t be changed without you releasing a new one thing. If someone else upgrades MySQL client version on the host, your code keeps using the version you tested with, like a static binary or like a Python venv with pinned versions or vendored dependencies. It is a lot simpler to manage dependencies this way; downside is if you one of your dependencies has a security advisory, it can’t be updated by rolling out a new version by someone else. You have to update it, so unowned code becomes more expensive in that scenario.