Kernel level exploits are more dangerous but also way less common, for a lot of places docker is sorta okay as a security boundary
To be more serious seurity is often in conflict with simplicity, efficiency, usability, and many other good things.
A baseline level of security (and avoidance of insecurities) should be expected everywhere, docker allows many places to easily reach it and is often a good enough tradeoff for many realities.
but I agree.