Open crew is such a mixed bag, I do it to find a crew that's already at sea doing something. It cuts out a lot of the wasted time finding a competent open crew. If I join a fresh boat there's a lot of open variables. What is the crew looking to do, when are they ready to leave the outpost, do they all have mics, what levels are they, etc.
Joining a boat mid-sea, you can see what quest they're on, what level that quest is, if the crew is working together, how much of the quest have they already completed, how stocked is their boat, are their sails angled into the wind, etc.
That makes it sound like I'm super picky, but I'm really not. If I can open crew join on a boat that's already out sailing, the time to actually start doing something just gets cut down drastically.