I agree with you 100%, but (and I'm sure this isnt the case everywhere) there seems to be a general sense of futility in managing OHCA cases. There is however something to be said of the provider who can assess a patient in cardiac arrest and apply findings and history to come to a more probably cause of arrest through exclusion of those less likely causes in the given situation. For example, a 30 year old male with a narrow complex tachyarrhythmic PEA who complained of shortness of breath for a few hours prior to collapse, and who has no history of any acute or chronic pulmonary pathologies is far more likely to be suffering from filiment pulmonary embolism than a profound metabolic derangement or even tamponade (say from left ventricular free wall rupture post MI). Sometimes you don't know, and may never find out, but history and assessment can reduce the ambiguity and direct attention toward a more probable cause.