Let's say some Heartbleed (which affected OpenSSL, primarily) happens again. With native packages, you update the package, restart a few things that depend on it with shared libraries, and you're patched. OS vendors are highly motivated to do this update, and often get pre-announcement info around security issues so it tends to go quickly.

With docker, someone has to rebuild every container that contains a copy of the library. This will necessarily lag and be delivered in a piecemeal fashion - if you have 5 containers, all of them need their own updates, which if you don't self-build and self-update, can take a while and is substantially more work than `apt get update && reboot`.

Incidentally, the same applies for most languages that prefer/require static linking.

As mentioned elsewhere in the thread, it's a tradeoff, and people should be aware of the tradeoffs around update and data lifecycle before making deployment decisions.