Pressure points aren't durability negation attacks but attacking spots where the human body doesn't have durability, it doesn't matter how strong you are, your durability comes from muscle mass and bones which you can train to endure more hits, on the other side there are parts in your body that aren't covered by bones and don't have much muscles covering them or even parts that lack both bones and muscles, this means it doesn't matter how you reinforce your body, you won't be able to make said parts more durable, at most you can train yourself to endure pain but that's another story.
The two more vulnerable parts are the eyes and balls, you legit don't have anything covering them which means there is absolutely nothing you can do to make those parts more resistant against attacks.
Tho not every pressure points damage the external of the body, a liver shot for example is an attack that damage the liver, how? Simple, even tho the liver is covered by muscles when you attack that part the muscles get pushed on the liver damaging it and inducing a lot of pain, here while you don't damage the muscle but what's behind them which can't be reinforced in any way, the only way to prevent this from happening would be having so many kg of muscles on that part that becomes physically impossible to push them but even if you train your muscles there they have still a low weigh and can be pushed anyway.
So... unless you have direct resistance to those parts you can't tank a PP attack.
Using a kid vs adult to prove PP might not work is an horrible example,
first because adults can get damaged by kids with the right PP, secondly as I said for the liver shot some parts might require a bare minimum of force to push the muscles which a kid might not have.
Another thing that is worth to mention is that characters that are at least street+ break this "it requires a bare minimum of force" as they scale fairly higher than peak human which means the can pretty much do the shit they want against normal body mass lol, a neck's muscle mass can't grew infinitely so after a certain AP every chin hit is outright KO.