Even if you build your own group, there's no safety net for the people in your group against you, if you happen to be the troll. As far as I know, if a PF says "Duty Completion" (which means 2-chest) it's not going to automatically lock the option in when you queue via Raid Finder.

Duty Complete/Duty Incomplete/Duty Completion also all sound really similar and are obtuse in their meaning.

With an absolute weekly lockout there needs to be protection against jerks, trolls, and ignorance. Joining should be a unanimous, informed decision, not something completely left up to the party leader.
When queue pops, when you hit Commence and the party is not eligible for 2-chest, a warning window for everyone in the party that says "This party is only eligible for 1 chest/is not eligible for chests. Accepting this queue means you agree to this" and requires additional input to fully accept. This is the same thing that happens when you hit Withdraw on DF - you get a pop-up that gives the leave penalty warning and requires more input to accept. Heck, make the button require you to hold it a couple seconds to fully accept. That's all anyone needs to realize something is off.

For that matter if any other kind of lockout would result, for example if someone queues O3S before clearing O1S/O2S for the week, another pop-up should occur to inform the player that High-end duty raids must be completed in sequential order every week and skipping to a later floor so makes them ineligible for any loot on prior floors.

There also should be a full Practice mode where no rewards, no lockout, no quest completion, no first-time bonus fulfillment, and no cutscenes occur.