Is such a distinction even useful if the "second wall" is what prevents the body from sustaining severe or permanent injury or worse? I mean, sure the brain may

Is such a distinction even useful if the "second wall" is what prevents the body from sustaining severe or permanent injury or worse? I mean, sure the brain may be limiting performance, but if all you end up with my removing the limit is a small performance gain at the expense of death then the "mental" limit is hardly distinguishable from an actual physical one.