The idea of being asked to fill a queue for extra incentive sounds interesting, but it would have to be implemented better. Like toggling it on like "yes I would like to receive these notifications". As someone who at least meets the mentor requirements and likes to help players sometimes, I wouldn't mind being asked to backfill a duty that's missing someone.

Though on the other hand it just sounds like less mysterious duty roulette. People already queue for those, knowing they'd get a random duty, and then instantly leave as soon as they see they're in Dun Scaith. So if they saw that duty pop up they'd be like "lmao no I'm too much of a coward" and cancel it.

Oh, and locking people out of stuff is pretty dumb. People already cancel stuff, like I said, because they don't want to do it even though they queued knowing they could get it.