I've seen this abuse repeatedly too. It's almost getting to the point where Duty Finder is completely useless.

What's worse is that I've often seen one person "quit" a party because they get frustrated, but they don't leave and take the 15-minute penalty. Instead, they just sit down and go AFK to make someone else take the 15-minute penalty for them. (The penalty only applies to the first person to leave the party.)

There absolutely must be an option to kick a leech from the party, preferably based on a simple majority. (i.e. 3 kick votes required in a light party, 5 kick votes in a full party)