Tanks dropping queue can be horrible. Just the other day, was queuing with with a group, and well, the following two pictures are from the 2nd time we had to go through the spam before we could get in.

They really should put a 1-5 minute cooldown on duty finder if you withdraw. The join in progress is not intended to be a way to skip bosses to try to get to the last boss faster, and fishing for groups in progress is abuse of the system.