I know of 2 A320's that took a lunch in the grass and a 744 that did the same as a result of the crew not becoming aware of the fact that the auto brake had dropped out. No major carnage in these accidents occurred except serious bent metal.
They were not the result of misunderstanding of what decel means, they were the result of firstly not noticing that the auto brake was not doing its job followed by a lack of support call to advise the PF as such.
This is why I am puzzled as to why we do not have an SOP that provides information as to the status of the auto brake on rollout but we do have one that provides information that is plainly freakin obvious.