It's just an old tradition for old Norwegians that goes back to the days of storing fish without modern day refrigeration.  The stuff can look nasty and it can taste nasty.  However, if someone makes it that actually knows what they are doing it can end up looking and tasting like normal fish.  But no matter how well it is cooked, there is no way to completely get rid of the odor that is generated from the fish.  Actually, for those folks that had the minor COVID symptoms of just losing their sense of taste and smell, that was a good time to try lutefisk.