> If we accept that any one person can take responsibility for their feelings then it follows that everyone is responsible for their own mind.

I don't think this follows! People are very different, so something can be genuinely true of a subset without generalising to everyone.

Crocker's Rules definitely wouldn't work for me, but it's explicit in them that they can only be self-invoked. Some people seem genuinely to be very thick-skinned (but easily annoyed by indirection and politeness) and able to 'take responsibility for their own feelings' in this sense. I doubt (m)any of them are truly unoffendable... and one could argue that they should be taking responsibility for their own feelings of frustration triggered by normal politeness... but I assume they know themselves well enough to know that they are better off when people try to be as direct as possible when interacting with them.

Where it breaks down is if/when they treat this as an objectively superior state of being and mode of interaction, and use it as an excuse to be rude to others.