How does it make it more difficult for the person who is actually on their job? Either the loot rules were stated in advanced in Party Finder, and they were ok with those rules joining, or in Duty Finder, they can Need the item and those people not on that job will always lose out. They can't need. They can only greed. And if they can only greed, in Duty Finder, without a Party Finder loot rules laid out in advanced, then don't be surprised if anyone else greeds or needs the item. Seems simple and not really hard on anyone.
So, you only roll Need if your current class can use it? If your current class cannot use it but another one will you NEVER greed it?
They can't. For your alts, they can only greed. The other people on their main? They can need. The people that greed will never win, unless the people that need only greed or pass.