When in Rome, do as the Romans do.
Not when the Romans are clearly idiots.

Waiting for more than a couple of parties before engaging a B is foolish IMHO. You risk screwing your group our of full credit by doing so, what sane leader is going to do that to their group?

Resetting is a terrible habit that just wastes people's time. Get enough people, kill it, end of story. Don't cry over 5 seals.

If your thought process is "I know there's probably a lot of people that are on the way to this, but screw them I want this for myself" Then yes, I see nothing wrong with selfish behaviour being punished.
No, my thought process (especially with a B) is to kill the damn thing before hundreds of people rock up and potentially bone me out of credit. Why is someone teleporting in from halfway around Eorzea entitled to credit from the hunt I found? They aren't, it's a rule that's been made up by hunt shells. Thankfully the hunt shells on Tonberry aren't quite this entitled, but there are quite a few individuals who seem to share this warped view of the world.