The fact OS patching is done by people whose entire job and profession is to keep systems patched matters - they are patched more often and faster. In addition,

The fact OS patching is done by people whose entire job and profession is to keep systems patched matters - they are patched more often and faster. In addition, the fact servers don't live long means it's easier to patch servers (since there's no need to patch a running system). So there's a very real difference here.