If crew members left divers to their own devices on the typical boatload we'd probably never get everyone in the water. I've seen people take three minutes just getting their fins on.
Yes, that is why they want the crew to do that work.
Years ago on a Florida trip I checked in at the office, showing an instructor card, and then went to the boat. The DM on board asked if I had a buddy, said it was required, and turned to the father son team setting up their gear next to where he was putting me to ask if I could join them. The father was clearly annoyed, and he asked, "That depends. Does he know what he's doing?"
The DM said, "I don't know." He looked at me and asked, "Do you know what you're doing?"
I said I had a pretty fair idea, so he put us together. It was a good thing. When the father/son team got so thoroughly confused that they reached an impasse on their gear setup, I showed them how to do it. They would have had no choice otherwise other than to got to the DM for help.
Fortunately for me, the shop owner (who had taken my registration) got on the boat, greeted me, and immediately hustled me off to join another group.