Well actually... 
 
There was a period there on live where the group EXP Bonus which amplifies the amount of EXP you earned for killing a mob, before that EXP is split amongst the group, was calculated based on number of people in the group.  But the splitting would only occur dividing by the number of players in range for the exp hit. 
 
Which only gave a slight bonus in our era since the maximum bonus is 20%. 
 
But during PoP this bonus was 80% at a maximum.  So having 4 dudes AFK in your group while you soloed across the zone would net an extra 80% EXP for you. 
		
		
		
		
		
			
		
		
		
		
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