just because people don't belive in gravity, it doesn't mean they won't fall down. The pressure point work or don't work argument has been going on as long as I've been in martial arts... probably longer... and I've always found the ones I use work, and the schematic for knockouts is usually workable if you're doing kata correctly.
Whoever started teaching pressure points as a separate skill did all kempo and karate players a real disservice, because the skill and access to them is usually found in the kata as designed by the master technicians who developed it. Thinking you can just walk up and "hit a spot" and drop somebody is like any other stupid concept that people who know little of the background skills will come up with in combat arts.
Traditional Chinese Medicine (TCM, for the novices) developed the "meridian system" to chart and define the body's energy system. The "pressure point phenomena" was developed as they found the effects of those hitting points and combinations of hitting points while actually treating patients... so the basis of hitting points IS found in TCM... but it isn't necessarily developed with the same definitions of point locations that are used for hitting points. Where "needle points" are very small and precise, the hitting points tsubos are about the size of a quarter, and generally located almost directly on top of the needling points in most cases (but not all).
Where needling is a method of introducing conductance or shorting out an electrical signal in the nervous system, the hitting points phenomena works almost totally off the autonomic nervous system, or the primary nerve bundle locations.
If you try to learn them from TCM, you will go crazy. If you learn them from kata, they will work fine for the applications of the kata and in self defense situations... and are not necessarily all directed at knocking someone out. Just as you, yourself,Underdog, use them as "motivators", they are often designed to disarm or disable someone from using a limb or from being able to respond to a trauma situation at the tsubo.
What is seldom taught or studied are the long term effects of hitting points on the body of the uke, and they are serious if repeated attacks to particular points in the body are used as targets. One observable phenomena is when there are constant attacks to the lung meridian points in the arms and wrist. The long term effect there is the development of asthma or breathing problems with fluid accumulations in the lungs.
Modern Western medicine has many treatments that shortcut those effects today, but if you go back to the time when all the science of hitting points was developed, the TCM treatments were the only available pathways to return someone to good health... which is why Dim Mak or "poison hand" developed such a reputation.
While there have been endless arguments both here and other places about whether or not you have to kill someone to train in Dim Mak, I would ask someone if they have to shoot someone with a pistol to know that it's dangerous? The idea that it only works if you produce a dead body is like those people who don't believe in gravity... until they fall down with some force.
In doing Aikido, people seldom realize how hard they actually throw themselves until they meet the mats for the first time (of being thrown hard). It's at that point that the "lights come on" and their path becomes "redirection".
Fighting against pressure points is kind of like being seasick... the first five minutes, you think you're going to die... the last five, you're afraid you won't...