If they were doing anything else besides objectives for esos they would stay. If they wanted DoL items or anything else, they wouldn't just complete and leave.

Also, who is to say that they won't join the pf group just to get a faster queue time. I am just thinking that they need to fix it for those that actually want to stay for things other than the esos, even if they just allow people to join in progress. I know people get together DoL farming groups and that's fine, it's the actual people who join to farm for gear or spoils that I am talking about.