That's too bad... about the one person setting the tone for the whole session. I think that is the responsibility of the person in charge of the group to keep that from always happening. To allow such behavior to continue is a good way to ruin a group. IMO

Not everyone can "run" a good support group. Everyone might think it's easy, easier than one on one, but if they go into it with that mindset they might easily miss the difficulty. (They might not be prepared to put in the time and effort it takes to run a good group....or rather, to facilitate a group so it's a good group for it's members.) Just my POV.