Ok, so what you are really talking about is defending against a low-skilled person swinging a blunt object at you. That is not the same thing as defending against a sword (sharp edge and point, sophisticated techniques), a staff (long reach, blunt thrusting and striking, sophisticated techniques), a spear (sharp point and cutting edge with a long reach, and really fast repeated thrusting stabs and sophisticated techniques), or a three-section staff (long reach, strikes, flexible tie-ups, sophisticated blocks and traps). Those are not the same thing as defending against Jimmy the weekend little-league coach swinging a baseball bat at you. Being able to defend against Jimmy with a bat is not the same as defending against traditional weapons made for war, used with sophisticated methods designed to be quickly lethal.
A bat is not a staff. A bat is not a sword. You might be able to take a glancing blow from a bat. But from a sword, with a sharp edge, that same glancing blow could sever tendons or muscles or limbs or arteries and you are dead.
If you want to defend against Jimmy with a bat, then develop that curriculum with the strengths and weaknesses of a bat in mind. Focus on the few untrained methods of attack that Jimmy is likely to use, with that bat. It isn’t the same thing as a sword or a staff.
Why do you assume I was saying that learning defense against a bat means you learn defense against all weapons? You are taking points I didn't make and arguing against them.
I'm saying if you learn defenses against a baseball swing or an overhand strike from a club (be it a bat, eskrima stick, asp, hammer, wrench, tire iron, etc) you've learned to defend against the majority of attacks with that type of weapon. Heck, you could even lump axes into that, as you're generally going to go for the handle instead of the end of the stick weapon.
I agree completely this won't help with swords, spears, staves, nunchucks, 3-section staff, firearms, attack dogs, and all of the other weapons you mentioned.
However, learning to defend against a club (which covers many different tools I mentioned above) you learn to defend against probably the most likely weapon you'll encounter on the street. Similarly, guns and knives are pretty common, at least in the US. I'd place staff next, as any long stick can basically be a staff. So it's not that you need to know how to defend every weapon, but there are a few that are very likely to be used against you.
I'd put swords, spears, nunchucks, and other martial arts or medieval weapons as less likely. Which brings us to...
So If you want to learn something about using a three-section staff, then go for it, but I don’t think learning unarmed defenses against it is realistic. I train sword, saber, staff, spear, double saber, double butterfly swords and double tomahawks, all in the context of Chinese martial arts. I don’t try to develop unarmed defenses against them. It’s not realistic, and it’s highly highly unlikely I’ll ever need them.
As I said earlier, it is incredibly unlikely I would be attacked with one of these, and for that reason I wouldn't train defense against them. However, I do not think that if I made unarmed defense against these weapons my focus, that it would be unrealistic to develop the ability to defend myself against the average user of them. At the very least, you would stand a chance to defend yourself.
The possibility of being attacked by someone with a 3-section-staff and the possibility of developing techniques to defend against it are two different things and two completely different arguments. The former addresses whether it's worth the time to study, while the later discusses whether it's even possible.
You'll also find you're on my side of the argument - you don't have to know the defenses against it to train with it. I agree with you that learning to defend against a master with the weapon is not going to be easy, if possible.
However, I disagree that you need to know how to defeat a master with a weapon for the self defense class to be useful. I disagree that anyone with a weapon has automatically won.