I find this to be least acurate with debian.. on other distros a patch may or may not install a new version of that package. that can bring changes to the behavior.
On debian stable the security issues are backported. So you can patch and be sure that there is no changes to the behavior of the system. It is basically the reason all vm's i manage are debian stable.
It is also true they never crash. But that is expected of linux. It is the extreme reliabillity that is the debian killer feature for me.