sadly, those journalists never give the whole story.
IT would be one thing if the plane had landed, tried to stop on the runway, but slid off the end.
AND quite another if the plane had made a normal stop on the runway and then slid off while exiting the runway onto a taxiway.
Runways can be pretty good braking but its the turnoff that will get you.
The article does mention freezing precip, and there may be more to it.