I think the lesson is stay aware of icing conditions, and if you must
absolutely fly in/near icing conditions - you better put the airframe
into the instrument scan.

Icing cannot be ignored, but that is precisely what this thread has
hypothesized.

First, the Caravan was flying in an area near icing. Strike One.

Second, this thread has hypothesized that the pilot failed to use
pitot heat, boots, and/or let the autopilot fly the plane into the
stall. Strikes 2,3,4.

Avoiding any one of these items likely would have precluded the
incident.