So-called "Mentors" and intentional disconnections.

[Vahlnir]

And some would say that you shouldn't run the roulette if you're not willing to run anything that might come up. It's similar to the people who queue for MSQ Roulette and then complain about the unskippable cutscenes. You are basically demonstrating the punishment for leaving isn't strict enough to prevent cherrypicking duties in a roulette. Most of those arguing the other side would rather people like that just don't queue and spare the other people who are willing to run the content the headache of "FULL PARTY".... "LIGHT PARTY"... "searching for players"

And some would say that the leave group function and duty finder debuff exist for a reason. Apparently it's wrong for people to have preferences though, Mentors especially.