When I throw a party, I like to label the foods in the spread. On a basic level, this communicates to everyone what the foods are (which is especially appreciated by any guests with allergies).
Moreover, labels are a convenient way to show off to your friends certain ingredients or recipe techniques. Certainly not everyone cares enough about food/cooking to do this, but in a circle of friends where crystallized orange peels and homemade crackers could be impressive and/or interesting, labels are good to use.
With labels, you don’t have to spend the party repeating yourself over and over, or trying to remember to tell someone that the dip has ham in it —whoops, too late— is miraculously vegetarian.