Fred, as much as DMs would love to NOT swap out your tank after coming up from a dive when the seas are tossing 3-5 feet, we'd have six people moving around on the deck at once trying to change tanks. And between falling over each other and leaning over the boat to hurl somebody's going to get hurt. Sometimes what appears to be a courtesy including extended briefings, and tank swapping is mainly an act of saftey to keep ops running smoothly. Not everyone on the boat has the diving prowess you imply you possess, so as a professional divemaster who gives briefings, swaps tanks, it's my job to make sure everyone gets back safely....including the knuckleheads we would all rather leave behind.
Pull back a stub....really.