(Its part of why torture doesnt work. The more people are freaked out, the more the brain reverts to a fight-or-flight baseline with faster reflexes and diminished cognitive skills)
Spoken like one of the millions that has not cracked under torture throughout history. No, the reason it doesn't work so well is that they don't know if you're just making shit up to avoid being tortured more. And even if you do tell they're likely to torture you some more because they'll assume you're still holding something back, so even if you get some truth it's maybe half-truth or mixed up with lies. If they had a safe and they knew for sure you have the combination and could instantly verify if you told them the truth or not, I bet torture would be 95%+ effective. What they want to achieve during torture is simply to pass the limit of how much pain you can take, whether you're almost passing out or delirious doesn't matter much as long as you don't die on them. Then they give you a break and say talk or we'll do that again.
There are a few people that can withstand torture but it's not because of amnesia, it's because they know that if they talk their friends will die or go to prison. I've never read a war documentary where the person claimed to have cracked and wanted to talk but mind blanked and simply was unable to, they've all either talked or been of the "the pain was out of this world but I'd never tell them anything, they'd have to kill me first" variety. Or for that matter, kill themselves first if they get the opportunity either before or after getting caught. I've read some stories from WWII that makes waterboarding sound very tame, under real not-pretending-to-be-civilized torture you are going to wish you were dead.