It's not a stupid question. That redundancy would be redundant, though.
I agree with Talrein's exclusion points. People who are queuing up without a full party should not get to be allowed to exclude people from their match-ups. Inclusiveness is the primary feature of the duty finder system.
But we should also understand that when someone forms a full party with a specific goal, it's obnoxious for people to join party without meeting the expectations of that full party.
Really, despite what people think they need, what they should be asking for is for the DF window to tell them if anyone in the party is new. It could display in the Reward area of the DF window, similar to the Adventurer in Need bonus.
What we really need is this:
Raid finder is an unnecessary addition, given that we have a richly featured Party Finder. Raid Finder's primary feature, the ability to exclude people who have not cleared content, is not enough to warrant an entirely separate interface for it.
We should just abolish the raid finder altogether, and add a simple indicator to the Duty Finder window that shows that someone in the party hasn't cleared the content.
With this in place, people who wanted to run with no preference could still DF it with randoms, while people who want to farm can form a full party via Party Finder, then easily see, before queuing, if all party members meet the expectation of having previously cleared.