Nice discussion. No absolutes in the field of combat, dojo or street.
Yes, some people will try to resist pain and get harder and tougher, specially on drugs and/or booze. Pain compliance just won't work on these people.
Yes, some peoples response to pain is to try to jump away from it, better to have "sticky hands" like Endo sensei than steel clamps which lose their grip.
Yes katame waza can and will hurt, and if necessary disable, but not everyone all of the time.
Yes Aikido works on so disturbing your opponent's (sorry, partner) balance that resistance is not possible, but some people's center is hard to find.
Yes Aikido is easier on the internet than anywhere else ;-)