They did not plan to ride on steep terrain so they left their beacons and shovels in their vehicles at the trailhead.
Even if they didnt plan on riding steep terrain, who's to say they wouldnt have needed them to save somebody that did? Please people, it's so easy to put a beacon on every time you get on your sled. USE THEM! This is one case where there may have been a completely different outcome if he had chosen to wear his beacon.
Condolences to the family and friends of those involved.