I've realised I have left out a very important concept - acceleration and decceleration injury.
The brain is in a hard bony cae, the skull, which protects it from direct injury. The energy of a punch is transferred to the skull and therefore does not affect the brain directly.
To cause a knock out you need to impart acceleration-deccelartion ie sudden movement of the whole skull and therefore the brain that suddenly starts and stops.
IMO the most efficient way to do this is with rotational motion - a punch that turns the head to one side or the other (a cross) or upward (an uppercut). This is why it is so important to tuck in your chin to stop this happening. And why the blows to the back of the head work becaue you can't "tuck your head in", or at least you are not used to it (shrugging up the shoulders).
Blows to the back of the head work probably best if you make the head nod.
I think Dillman's knock out points on the jaw and head come from imparting this rotational energy with a quick jab. Possibly with a distracter first, especially on pliant victims in demonstrations.
I think the technique you are talking baout is pretty safe as the occiput is a very thick bit of bone and the brain itself will be protected. Just look after your unconscious uke.